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  • 1. Alku, Paavo
    et al.
    Airas, Matti
    Björkner, Eva
    KTH, School of Computer Science and Communication (CSC), Speech, Music and Hearing, TMH.
    Sundberg, Johan
    KTH, School of Computer Science and Communication (CSC), Speech, Music and Hearing, TMH.
    An amplitude quotient based method to analyze changes in the shape of the glottal pulse in the regulation of vocal intensity2006In: Journal of the Acoustical Society of America, ISSN 0001-4966, E-ISSN 1520-8524, Vol. 120, no 2, p. 1052-1062Article in journal (Refereed)
    Abstract [en]

    This study presents an approach to visualizing intensity regulation in speech. The method expresses a voice sample in a two-dimensional space using amplitude-domain values extracted from the glottal flow estimated by inverse filtering. The two-dimensional presentation is obtained by expressing a time-domainmeasure of the glottal pulse, the amplitude quotient (AQ), as a function of the negative peak amplitude of the flow derivative (d(peak)). The regulation of vocal intensity was analyzed with the proposed method from voices varying from extremely soft to very loud with a SPL range of approximately 55 dB. When vocal intensity was increased, the speech samples first showed a rapidly decreasing trend as expressed on the proposed AQ-d(peak) graph. When intensity was further raised, the location of the samples converged toward a horizontal line, the asymptote of a hypothetical hyperbola. This behavior of the AQ-d(peak) graph indicates that the intensity regulation strategy changes from laryngeal to respiratory mechanisms and the method chosen makes it possible to quantify how control mechanisms underlying the regulation of vocal intensity change gradually between the two means. The proposed presentation constitutes an easy-to-implement method to visualize the function of voice production in intensity regulation because the only information needed is the glottal flow wave form estimated by inverse filtering the acoustic speech pressure signal.

  • 2. Arnela, Marc
    et al.
    Blandin, Rémi
    Dabbaghchian, Saeed
    KTH, School of Computer Science and Communication (CSC), Speech, Music and Hearing, TMH, Speech Communication and Technology.
    Guasch, Oriol
    Alías, Francesc
    Pelorson, Xavier
    Van Hirtum, Annemie
    Engwall, Olov
    KTH, School of Computer Science and Communication (CSC), Speech, Music and Hearing, TMH, Speech Communication and Technology.
    Influence of lips on the production of vowels based on finite element simulations and experiments2016In: Journal of the Acoustical Society of America, ISSN 0001-4966, E-ISSN 1520-8524, Vol. 139, no 5, p. 2852-2859Article in journal (Refereed)
    Abstract [en]

    Three-dimensional (3-D) numerical approaches for voice production are currently being investigated and developed. Radiation losses produced when sound waves emanate from the mouth aperture are one of the key aspects to be modeled. When doing so, the lips are usually removed from the vocal tract geometry in order to impose a radiation impedance on a closed cross-section, which speeds up the numerical simulations compared to free-field radiation solutions. However, lips may play a significant role. In this work, the lips' effects on vowel sounds are investigated by using 3-D vocal tract geometries generated from magnetic resonance imaging. To this aim, two configurations for the vocal tract exit are considered: with lips and without lips. The acoustic behavior of each is analyzed and compared by means of time-domain finite element simulations that allow free-field wave propagation and experiments performed using 3-D-printed mechanical replicas. The results show that the lips should be included in order to correctly model vocal tract acoustics not only at high frequencies, as commonly accepted, but also in the low frequency range below 4 kHz, where plane wave propagation occurs.

  • 3. Arnela, Marc
    et al.
    Dabbaghchian, Saeed
    KTH, School of Computer Science and Communication (CSC), Speech, Music and Hearing, TMH.
    Blandin, Rémi
    Guasch, Oriol
    Engwall, Olov
    KTH, School of Computer Science and Communication (CSC), Speech, Music and Hearing, TMH.
    Hirtum, Annemie Van
    Pelorson, Xavier
    Influence of vocal tract geometry simplifications on the numerical simulation of vowel sounds2016In: Journal of the Acoustical Society of America, ISSN 0001-4966, E-ISSN 1520-8524, Vol. 140, no 3, p. 1707-1718Article in journal (Refereed)
    Abstract [en]

    For many years, the vocal tract shape has been approximated by one-dimensional (1D) area functions to study the production of voice. More recently, 3D approaches allow one to deal with the complex 3D vocal tract, although area-based 3D geometries of circular cross-section are still in use. However, little is known about the influence of performing such a simplification, and some alternatives may exist between these two extreme options. To this aim, several vocal tract geometry simplifications for vowels [ɑ], [i], and [u] are investigated in this work. Six cases are considered, consisting of realistic, elliptical, and circular cross-sections interpolated through a bent or straight midline. For frequencies below 4–5 kHz, the influence of bending and cross-sectional shape has been found weak, while above these values simplified bent vocal tracts with realistic cross-sections are necessary to correctly emulate higher-order mode propagation. To perform this study, the finite element method (FEM) has been used. FEM results have also been compared to a 3D multimodal method and to a classical 1D frequency domain model.

  • 4. Auregan, Yves
    et al.
    Farooqui, Maaz
    Groby, Jean-Phillipe
    Low frequency sound attenuation in a flow duct using a thin slow sound material2016In: Journal of the Acoustical Society of America, ISSN 0001-4966, E-ISSN 1520-8524, Vol. 139, no 5, p. EL149-EL153Article in journal (Refereed)
    Abstract [en]

    A thin subwavelength material that can be flush mounted in a duct and that gives an attenuation band at low frequencies in air flow channels is presented. To decrease the material thickness, the sound is slowed in the material using folded side branch tubes. The impedance of the material is compared to the optimal value given by the Cremer condition, which can differ greatly from the air characteristic impedance. Grazing flow on this material increases the losses at the interface between the flow and the material.

  • 5.
    Bjurström, Henrik
    et al.
    KTH, School of Architecture and the Built Environment (ABE), Civil and Architectural Engineering, Soil and Rock Mechanics.
    Rydén, Nils
    KTH, School of Architecture and the Built Environment (ABE), Civil and Architectural Engineering, Soil and Rock Mechanics.
    Detecting the thickness mode frequency in a concrete plate using backward wave propagation2016In: Journal of the Acoustical Society of America, ISSN 0001-4966, E-ISSN 1520-8524, Vol. 139, no 2, p. 649-657Article in journal (Refereed)
    Abstract [en]

    Material stiffness and plate thickness are the two key parameters when performing quality assurance/quality control on pavement structures. In order to estimate the plate thickness non-destructively, theImpact Echo (IE) method can be utilized to extract the thickness resonance frequency. An alternativeto IE for estimating the thickness resonance frequency of a concrete plate, and to subsequently enablethickness determination, is presented in this paper. The thickness resonance is often revealed as asharp peak in the frequency spectrum when contact receivers are used in seismic testing. Due to a lowsignal-to-noise ratio, IE is not ideal when using non-contact microphone receivers. In studying thecomplex Lamb wave dispersion curves at a frequency infinitesimally higher than the thickness frequency,it is seen that two counter-directed waves occur at the same frequency but with phase velocitiesin opposite directions. Results show that it is possible to detect the wave traveling with anegative phase velocity using both accelerometers and air-coupled microphones as receivers. Thisalternative technique can possibly be used in non-contact scanning measurements based on aircoupled microphones.

  • 6.
    Bodén, Hans
    KTH, School of Engineering Sciences (SCI), Aeronautical and Vehicle Engineering, MWL Structural and vibroacoustics.
    Experimental source characterization techniques for studying the acoustic properties of perforates under high level acoustic excitation2011In: Journal of the Acoustical Society of America, ISSN 0001-4966, E-ISSN 1520-8524, Vol. 130, no 5, p. 2639-2647Article in journal (Refereed)
    Abstract [en]

    This paper discusses experimental techniques for obtaining the acoustic properties of in-duct samples with non-linear acoustic characteristic. The methods developed are intended both for studies of non-linear energy transfer to higher harmonics for samples only accessible from one side such as wall treatment in aircraft engine ducts or automotive exhaust systems and for samples accessible from both sides such as perforates or other top sheets. When harmonic sound waves are incident on the sample nonlinear energy transfer results in sound generation at higher harmonics at the sample (perforate) surface. The idea is that these sources can be characterized using linear system identification techniques similar to one-port or two-port techniques which are traditionally used for obtaining source data for in-duct sources such as IC-engines or fans. The starting point will be so called polyharmonic distortion modeling which is used for characterization of nonlinear properties of microwave systems. It will be shown how acoustic source data models can be expressed using this theory. Source models of different complexity are developed and experimentally tested. The results of the experimental tests show that these techniques can give results which are useful for understanding non-linear energy transfer to higher harmonics.

  • 7.
    Boij, Susann
    KTH, School of Engineering Sciences (SCI), Aeronautical and Vehicle Engineering, Marcus Wallenberg Laboratory MWL. KTH, School of Engineering Sciences (SCI), Centres, Linné Flow Center, FLOW.
    Flow effects on the acoustic end correction of a sudden in-duct area expansion2009In: Journal of the Acoustical Society of America, ISSN 0001-4966, E-ISSN 1520-8524, Vol. 126, no 3, p. 995-1004Article in journal (Refereed)
    Abstract [en]

    For scattering of plane waves at a sudden area expansion in a duct, the presence of flow may significantly alter the reactive properties. This paper studies the influence of a mean flow field and unstable separated flow on the reactive properties of the expansion, formulated as an end correction. Theoretical and experimental results show that the expansion end correction is significantly affected by the flow and hydrodynamic waves excited at the edge of the expansion. The effects are different in three regions where the Strouhal number is small, of order 1, and large. The influence is most significant at Strouhal numbers of the order 1, with specific limiting values for large and small Strouhal numbers, respectively. In the analytic model, an important feature is the shear layer at the edge modeled as a vortex sheet with the unsteady Kutta condition applied at the edge. The influence of Mach number, Helmholtz number, and area expansion ratio is studied, and a quasistationary, small Strouhal number, approximation yields an expression for the end correction. Further, the influence of edge condition is explored, emphasizing the importance of interaction between sound and unsteady vorticity shedding at the edge of the area expansion.

  • 8.
    Bolin, Karl
    et al.
    KTH, School of Engineering Sciences (SCI), Aeronautical and Vehicle Engineering, Marcus Wallenberg Laboratory MWL.
    Almgren, Martin
    Ohlsson, Esbjörn
    Karasalo, Ilkka
    KTH, School of Engineering Sciences (SCI), Aeronautical and Vehicle Engineering, Marcus Wallenberg Laboratory MWL.
    Long term estimations of low frequency noise levels over water from an off-shore wind farm2014In: Journal of the Acoustical Society of America, ISSN 0001-4966, E-ISSN 1520-8524, Vol. 135, no 3, p. 1106-1114Article in journal (Refereed)
    Abstract [en]

    This article focuses on computations of low frequency sound propagation from an off-shore wind farm. Two different methods for sound propagation calculations are combined with meteorological data for every 3 hours in the year 2010 to examine the varying noise levels at a reception point at 13 km distance. It is shown that sound propagation conditions play a vital role in the noise impact from the off-shore wind farm and ordinary assessment methods can become inaccurate at longer propagation distances over water. Therefore, this paper suggests that methodologies to calculate noise immission with realistic sound speed profiles need to be combined with meteorological data over extended time periods to evaluate the impact of low frequency noise from modern off-shore wind farms.

  • 9.
    Bolin, Karl
    et al.
    KTH, School of Engineering Sciences (SCI), Aeronautical and Vehicle Engineering, Marcus Wallenberg Laboratory MWL.
    Boue, Mathieu
    KTH, School of Engineering Sciences (SCI), Aeronautical and Vehicle Engineering, Marcus Wallenberg Laboratory MWL.
    Karasalo, Ilkka
    KTH, School of Engineering Sciences (SCI), Aeronautical and Vehicle Engineering, Marcus Wallenberg Laboratory MWL.
    Long range sound propagation over a sea surface2009In: Journal of the Acoustical Society of America, ISSN 0001-4966, E-ISSN 1520-8524, Vol. 126, no 5, p. 2191-2197Article in journal (Refereed)
    Abstract [en]

    This paper describes methodology and results from a model-based analysis of data on sound transmission from controlled sound sources at sea to a 10-km distant shore. The data consist of registrations of sound transmission loss together with concurrently collected atmospheric data at the source and receiver locations. The purpose of the analysis is to assess the accuracy of methods for transmission loss prediction in which detailed data on the local geography and atmospheric conditions are used for computation of the sound field. The results indicate that such sound propagation predictions are accurate and reproduce observed variations in the sound level as function of time in a realistic way. The results further illustrate that the atmospheric model must include a description of turbulence effects to ensure predicted noise levels to remain realistically high during periods of sound shadow. (C) 2009 Acoustical Society of America. [DOI: 10.1121/1.3238236]

  • 10.
    Bolin, Karl
    et al.
    KTH, School of Engineering Sciences (SCI), Aeronautical and Vehicle Engineering, Marcus Wallenberg Laboratory MWL.
    Åbom, Mats
    KTH, School of Engineering Sciences (SCI), Aeronautical and Vehicle Engineering, Marcus Wallenberg Laboratory MWL.
    Air-borne sound generated by sea waves2010In: Journal of the Acoustical Society of America, ISSN 0001-4966, E-ISSN 1520-8524, Vol. 127, no 5, p. 2771-2779Article in journal (Refereed)
    Abstract [en]

    This paper describes a semi-empiric model and measurements of air-borne sound generated by breaking sea waves. Measurements have been performed at the Baltic Sea. Shores with different slopes and sediment types have been investigated. Results showed that the sound pressure level increased from 60 dB at 0.4 m wave height to 78 dB at 2.0 m wave height. The 1/3 octave spectrum was dependent on the surf type. A scaling model based on the dissipated wave power and a surf similarity parameter is proposed and compared to measurements. The predictions show satisfactory agreement to the measurements. (C) 2010 Acoustical Society of America. [DOI: 10.1121/1.3327815]

  • 11.
    Cartling, Bo
    KTH, School of Engineering Sciences (SCI), Physics.
    Beating frequency and amplitude modulation of the piano tone due to coupling of tones2005In: Journal of the Acoustical Society of America, ISSN 0001-4966, E-ISSN 1520-8524, Vol. 117, no 4, p. 2259-2267Article in journal (Refereed)
    Abstract [en]

    The influence on a piano tone from weak coexcitation of damped adjacent tones due to coupling via the bridge is studied. The frequency and amplitude modulation of the sound resulting from coexcitation of one strong and one or two weak tones is analyzed. One weak tone causes frequency and amplitude modulation of the sound, and two weak tones produce beating frequency and amplitude modulation, where the beatings of the two modulations are of opposite phase. By digital recording of the sound of piano tones, the appearance of these phenomena is verified. The audibility of the observed frequency and amplitude modulation is discussed in terms of previously determined detection thresholds. The beating character of both frequency and amplitude modulations, however, distinguishes the phenomena from those previously studied and prompts further psychoacoustic investigations. It is shown that detuning of unison strings may significantly increase the frequency deviation of the frequency modulation in conjunction with affected amplitude modulation. The modulatory effects of coupling to adjacent tones therefore may possibly be utilized in the tuning process. A coupling of tones analogous to the situation in a piano may arise in other stringed musical instruments transferring string vibrations to a soundboard via a bridge.

  • 12.
    Cuenca, Jacques
    et al.
    KTH, School of Engineering Sciences (SCI), Aeronautical and Vehicle Engineering.
    Göransson, Peter
    KTH, School of Engineering Sciences (SCI), Aeronautical and Vehicle Engineering.
    Inverse estimation of the elastic and anelastic properties of the porous frame of anisotropic open-cell foams2012In: Journal of the Acoustical Society of America, ISSN 0001-4966, E-ISSN 1520-8524, Vol. 132, no 2, p. 621-629Article in journal (Refereed)
    Abstract [en]

    This paper presents a method for simultaneously identifying both the elastic and anelastic properties of the porous frame of anisotropic open-cell foams. The approach is based on an inverse estimation procedure of the complex stiffness matrix of the frame by performing a model fit of a set of transfer functions of a sample of material subjected to compression excitation in vacuo. The material elastic properties are assumed to have orthotropic symmetry and the anelastic properties are described using a fractional-derivative model within the framework of an augmented Hooke's law. The inverse estimation problem is formulated as a numerical optimization procedure and solved using the globally convergent method of moving asymptotes. To show the feasibility of the approach a numerically generated target material is used here as a benchmark. It is shown that the method provides the full frequency-dependent orthotropic complex stiffness matrix within a reasonable degree of accuracy.

  • 13.
    Dahl, Sofia
    et al.
    KTH, School of Computer Science and Communication (CSC), Speech, Music and Hearing, TMH.
    Granqvist, Svante
    KTH, School of Computer Science and Communication (CSC), Speech, Music and Hearing, TMH.
    Ability to determine continuous drift in auditory sequences: Evidence for bias in listeners' perception of tempo2005In: Journal of the Acoustical Society of America, ISSN 0001-4966, E-ISSN 1520-8524Article in journal (Other academic)
  • 14.
    Dickson, Crispin
    KTH, School of Engineering Sciences (SCI), Aeronautical and Vehicle Engineering, Marcus Wallenberg Laboratory MWL.
    A method for time-varying annoyance rating of aircraft noise2009In: Journal of the Acoustical Society of America, ISSN 0001-4966, E-ISSN 1520-8524, Vol. 126, no 1, p. 1-3Article in journal (Refereed)
    Abstract [en]

    The method of continuous judgment by category is used and evaluated to measure time-varying attributes in aircraft flyover sounds. The results are also used to estimate preference between the different experimental sounds. Jurors were asked to rate perceived annoyance on a Borg CR 100 scale continuously during the playback of 11 flyover sequences and the results showed differences in perception in the time segment where the sound had been modified. The method can be used to evaluate maximum perceived annoyance, threshold levels, duration of perceptual presence temporal integration in perception, and perceptual mixtures over time.

  • 15.
    Drioli, Carlo
    KTH, School of Computer Science and Communication (CSC), Speech, Music and Hearing, TMH.
    A flow waveform-matched low-dimensional glottal model based on physical knowledge2005In: Journal of the Acoustical Society of America, ISSN 0001-4966, E-ISSN 1520-8524, Vol. 117, no 5, p. 3184-3195Article in journal (Refereed)
    Abstract [en]

    The purpose of this study is to explore the possibility for physically based mathematical models of the voice source to accurately reproduce inverse filtered glottal volume-velocity waveforms. A low-dimensional, self-oscillating model of the glottal source with waveform-matching properties is proposed. The model relies on a lumped mechano-aerodynamic scheme loosely inspired by the one-and multimass lumped models. The vocal folds are represented by a single mechanical resonator and a propagation line which takes into account the vertical phase differences. The vocal-fold displacement is coupled to the glottal flow by means of an aerodynamic driving block which includes a general parametric nonlinear component. The principal characteristics of the flow-induced oscillations are retained, and the overall model is able to match inverse-filtered glottal flow signals. The method offers in principle the possibility of performing transformations of the glottal flow by acting on the physiologically based parameters of the model. This is a desirable property, e.g., for speech synthesis applications. The model was tested on a data set which included inverse-filtered glottal flow waveforms of different characteristics. The results demonstrate the possibility of reproducing natural speech waveforms with high accuracy, and of controlling important characteristics of the synthesis such as pitch.

  • 16. Echternach, Matthias
    et al.
    Doellinger, Michael
    Sundberg, Johan
    KTH, School of Computer Science and Communication (CSC), Speech, Music and Hearing, TMH, Music Acoustics.
    Traser, Louisa
    Richter, Bernhard
    Vocal fold vibrations at high soprano fundamental frequencies2013In: Journal of the Acoustical Society of America, ISSN 0001-4966, E-ISSN 1520-8524, Vol. 133, no 2, p. EL82-EL87Article in journal (Refereed)
    Abstract [en]

    Human voice production at very high fundamental frequencies is not yet understood in detail. It was hypothesized that these frequencies are produced by turbulences, vocal tract/vocal fold interactions, or vocal fold oscillations without closure. Hitherto it has been impossible to visually analyze the vocal mechanism due to technical limitations. Latest high-speed technology, which captures 20 000 frames/s, using transnasal endoscopy was applied. Up to 1568Hz human vocal folds do exhibit oscillations with complete closure. Therefore, the recent results suggest that human voice production at very high F0s up to 1568Hz is not caused by turbulence, but rather by airflow modulation from vocal fold oscillations. (C) 2013 Acoustical Society of America

  • 17. Echternach, Matthias
    et al.
    Sundberg, Johan
    KTH, School of Computer Science and Communication (CSC), Speech, Music and Hearing, TMH.
    Baumann, Tobias
    Markl, Michael
    Richter, Bernhard
    Vocal tract area functions and formant frequencies in opera tenors' modal and falsetto registers2011In: Journal of the Acoustical Society of America, ISSN 0001-4966, E-ISSN 1520-8524, Vol. 129, no 6, p. 3955-3963Article in journal (Refereed)
    Abstract [en]

    According to recent model investigations, vocal tract resonance is relevant to vocal registers. However, no experimental corroboration of this claim has been published so far. In the present investigation, ten professional tenors' vocal tract configurations were analyzed using MRI volumetry. All subjects produced a sustained tone on the pitch F4 (349 Hz) on the vowel /a/(1) in modal and (2) in falsetto register. The area functions were estimated from the MRI data and their associated formant frequencies were calculated. In a second condition the same subjects repeated the same tasks in a sound treated room and their formant frequencies were estimated by means of inverse filtering. In both recordings similar formant frequencies were observed. Vocal tract shapes differed between modal and falsetto register. In modal as compared to falsetto the lip opening and the oral cavity were wider and the first formant frequency was higher. In this sense the presented results are in agreement with the claim that the formant frequencies differ between registers.

  • 18.
    Elowsson, Anders
    et al.
    KTH, School of Computer Science and Communication (CSC), Speech, Music and Hearing, TMH.
    Friberg, Anders
    KTH, School of Computer Science and Communication (CSC), Speech, Music and Hearing, TMH.
    Modeling the perception of tempo2015In: Journal of the Acoustical Society of America, ISSN 0001-4966, E-ISSN 1520-8524, Vol. 137, no 6, p. 3163-3177Article in journal (Refereed)
    Abstract [en]

    A system is proposed in which rhythmic representations are used to model the perception of tempo in music. The system can be understood as a five-layered model, where representations are transformed into higher-level abstractions in each layer. First, source separation is applied (Audio Level), onsets are detected (Onset Level), and interonset relationships are analyzed (Interonset Level). Then, several high-level representations of rhythm are computed (Rhythm Level). The periodicity of the music is modeled by the cepstroid vector-the periodicity of an interonset interval (IOI)-histogram. The pulse strength for plausible beat length candidates is defined by computing the magnitudes in different IOI histograms. The speed of the music is modeled as a continuous function on the basis of the idea that such a function corresponds to the underlying perceptual phenomena, and it seems to effectively reduce octave errors. By combining the rhythmic representations in a logistic regression framework, the tempo of the music is finally computed (Tempo Level). The results are the highest reported in a formal benchmarking test (2006-2013), with a P-Score of 0.857. Furthermore, the highest results so far are reported for two widely adopted test sets, with an Acc1 of 77.3% and 93.0% for the Songs and Ballroom datasets.

  • 19.
    Elowsson, Anders
    et al.
    KTH, School of Computer Science and Communication (CSC), Speech, Music and Hearing, TMH.
    Friberg, Anders
    KTH, School of Computer Science and Communication (CSC), Speech, Music and Hearing, TMH.
    Predicting the perception of performed dynamics in music audio with ensemble learning2017In: Journal of the Acoustical Society of America, ISSN 0001-4966, E-ISSN 1520-8524, Vol. 141, no 3, p. 2224-2242Article in journal (Refereed)
    Abstract [en]

    By varying the dynamics in a musical performance, the musician can convey structure and different expressions. Spectral properties of most musical instruments change in a complex way with the performed dynamics, but dedicated audio features for modeling the parameter are lacking. In this study, feature extraction methods were developed to capture relevant attributes related to spectral characteristics and spectral fluctuations, the latter through a sectional spectral flux. Previously, ground truths ratings of performed dynamics had been collected by asking listeners to rate how soft/loud the musicians played in a set of audio files. The ratings, averaged over subjects, were used to train three different machine learning models, using the audio features developed for the study as input. The highest result was produced from an ensemble of multilayer perceptrons with an R2 of 0.84. This result seems to be close to the upper bound, given the estimated uncertainty of the ground truth data. The result is well above that of individual human listeners of the previous listening experiment, and on par with the performance achieved from the average rating of six listeners. Features were analyzed with a factorial design, which highlighted the importance of source separation in the feature extraction.

  • 20.
    Enflo, Bengt Olof
    et al.
    KTH, School of Engineering Sciences (SCI), Mechanics.
    Hedberg, C M
    Rudenko, O V
    Resonant properties of a nonlinear dissipative layer excited by a vibrating boundary: Q-factor and frequency response2005In: Journal of the Acoustical Society of America, ISSN 0001-4966, E-ISSN 1520-8524, Vol. 117, no 2, p. 601-612Article in journal (Refereed)
    Abstract [en]

    Simplified nonlinear evolution equations describing non-steady-state forced vibrations in an acoustic resonator having one closed end and the other end periodically oscillating are derived. An approach based on a nonlinear functional equation is used. The nonlinear Q-factor and the nonlinear frequency response of the resonator are calculated for steady-state oscillations of both inviscid and dissipative media. The general expression for the mean intensity of the acoustic wave in terms of the characteristic value of a Mathieu function is derived. The process of development of a standing wave is described analytically on the base of exact nonlinear solutions for different laws of periodic motion of the wall. For harmonic excitation the wave profiles are described by Mathieu functions, and their mean energy characteristics by the corresponding eigenvalues. The sawtooth-shaped motion of the boundary leads to a similar process of evolution of the profile, but the solution has a very simple form. Some possibilities to enhance the Q-factor of a nonlinear system by suppression of nonlinear energy losses are discussed.

  • 21.
    Fabiani, Marco
    et al.
    KTH, School of Computer Science and Communication (CSC), Speech, Music and Hearing, TMH, Music Acoustics.
    Friberg, Anders
    KTH, School of Computer Science and Communication (CSC), Speech, Music and Hearing, TMH, Music Acoustics.
    Influence of pitch, loudness, and timbre on the perception of instrument dynamics2011In: Journal of the Acoustical Society of America, ISSN 0001-4966, E-ISSN 1520-8524, Vol. 130, no 4, p. EL193-EL199Article in journal (Refereed)
    Abstract [en]

    The effect of variations in pitch, loudness, and timbre on the perception of the dynamics of isolated instrumental tones is investigated. A full factorial design was used in a listening experiment. The subjects were asked to indicate the perceived dynamics of each stimulus on a scale from pianissimo to fortissimo. Statistical analysis showed that for the instruments included (i.e., clarinet, flute, piano, trumpet, and violin) timbre and loudness had equally large effects, while pitch was relevant mostly for the first three. The results confirmed our hypothesis that loudness alone is not a reliable estimate of the dynamics of musical tones.

  • 22.
    Farooqui, Maaz
    et al.
    KTH, School of Engineering Sciences (SCI), Aeronautical and Vehicle Engineering.
    Elnady, Tamer
    Akl, Wael
    Sound attenuation in ducts using locally resonant periodic aluminum patches2016In: Journal of the Acoustical Society of America, ISSN 0001-4966, E-ISSN 1520-8524, Vol. 139, no 6, p. 3276-3286Article in journal (Refereed)
    Abstract [en]

    In recent years, the control of low frequency noise has received a lot of attention for several applications. Traditional passive noise control techniques using Helmholtz resonators have size limitations in the low frequency range because of the long wavelength. Promising noise reductions, with flush mounted aluminum patches with no size problems can be obtained using local resonance phenomenon implemented in acoustic metamaterial techniques. The objective of this work is to introduce locally resonant thin aluminum patches flush mounted to a duct walls aiming at creating frequency stop bands in a specific frequency range. Green's function is used within the framework of interface response theory to predict the amount of attenuation of the local resonant patches. The two-port theory and finite elements are also used to predict the acoustic performance of these patches. No flow measurements were conducted and show good agreement with the models. The effect of varying the damping and the masses of the patches are used to expand the stop bandwidth and the effect of both Bragg scattering and the locally resonant mechanisms was demonstrated using mathematical models. The effect of the arrays of patches on the effective dynamic density and bulk modulus has also been investigated.

  • 23. Farooqui, Maaz
    et al.
    Elnady, Tamer
    Akl, Wael
    Validation of low frequency noise attenuation using locally resonant patches2016In: Journal of the Acoustical Society of America, ISSN 0001-4966, E-ISSN 1520-8524Article in journal (Refereed)
    Abstract [en]

    Since conventional silencers in acoustic ducts have problems of size limitations at low frequencies and being prone to high backpressure, locally resonant aluminum patches are introduced in acoustic duct walls aiming at creating frequency stop bands in the low frequency region (below 1 KHz). With these flush mounted patches, promising noise reductions, with no such drawbacks, can be obtained, building on local resonance phenomenon implemented in acoustic metamaterials techniques. The objective of the current paper is to experimentally validate the performance of an array of flexible side-wall-mounted patches inside ducts. The experimental results are compared with Analytical Green's function method as well as Numerical Finite Element Method and a close agreement was found. The results show that the presence of the patches singly or periodically can play a prominent role in designing any acousticbandgap materials. The effect of the arrays of patches on the effective dynamic density and bulk modulushas also been investigated.

  • 24.
    Feng, Leiping
    et al.
    KTH, Superseded Departments, Vehicle Engineering.
    Liu, M. H.
    Nilsson, A.
    Experimental study of structure-borne sound transmission loss of mechanical joints2001In: Journal of the Acoustical Society of America, ISSN 0001-4966, E-ISSN 1520-8524, Vol. 110, no 3, p. 1391-1397Article in journal (Refereed)
    Abstract [en]

    A mechanical joint is one of the most effective ways to reduce the transmission of structure-borne sound. In order to increase the transmission loss, heavily damped joints are often used, which, in many cases, will reduce the structure integrity and hence can only be used in limited cases. In this study attention is focused on a type of resonant joint, i.e., a joint which will increase the transmission loss but will not reduce the structure integrity. The study is based on experiments in a one-dimensional structure. It is found that by adjusting the overlap of the joint, the transmission loss of 30 dB can be obtained at a certain frequency range without adding any dissipative materials. The mechanism of this high transmission loss is the cantilever-type resonance. The resonant frequency can be predicted precisely. The influence of extra dissipative material is investigated. The performance of the same joint in a finite structure is also examined by using the concept of vibrational insertion loss. When there is a certain damping in a finite system, a rather high insertion loss can still be achieved by using the above-mentioned joint, but the resonant frequency is shifted to higher end. It seems that the effective length of the cantilever is shortened by the finiteness.

  • 25.
    Feng, Leping
    KTH, School of Engineering Sciences (SCI), Aeronautical and Vehicle Engineering, MWL Structural and vibroacoustics.
    Active control of structurally radiated sound using multi-actuator method1995In: Journal of the Acoustical Society of America, ISSN 0001-4966, E-ISSN 1520-8524, Vol. 98, no 1, p. 397-402Article in journal (Refereed)
  • 26.
    Finnveden, Svante
    et al.
    KTH, School of Engineering Sciences (SCI), Aeronautical and Vehicle Engineering, Marcus Wallenberg Laboratory MWL.
    Hörlin, Nils-Erik
    KTH, School of Engineering Sciences (SCI), Aeronautical and Vehicle Engineering, Marcus Wallenberg Laboratory MWL.
    Barbagallo, Mathias
    KTH, School of Engineering Sciences (SCI), Aeronautical and Vehicle Engineering, Marcus Wallenberg Laboratory MWL.
    Dynamic characterization of viscoelastic porous foams used in vehicles based on an inverse finite element method2014In: Journal of the Acoustical Society of America, ISSN 0001-4966, E-ISSN 1520-8524, Vol. 135, no 4, p. 1834-1843Article in journal (Refereed)
    Abstract [en]

    Viscoelastic properties of porous materials, typical of those used in vehicles for noise insulation and absorption, are estimated from measurements and inverse finite element procedures. The measurements are taken in a near vacuum and cover a broad frequency range: 20 Hz to 1 kHz. The almost cubic test samples were made of 25mm foam covered by a "heavy layer" of rubber. They were mounted in a vacuum chamber on an aluminum table, which was excited in the vertical and horizontal directions with a shaker. Three kinds of response are measured allowing complete estimates of the viscoelastic moduli for isotropic materials and also providing some information on the degree of material anisotropicity. First, frequency independent properties are estimated, where dissipation is described by constant loss factors. Then, fractional derivative models that capture the variation with frequency of the stiffness and damping are adapted. The measurement setup is essentially two-dimensional and calculations are three-dimensional and for a state of plane strain. The good agreement between measured and calculated response provides some confidence in the presented procedures. If, however, the material model cannot fit the measurements well, the inverse procedure yields a certain degree of arbitrariness to the parameter estimation.

  • 27.
    Friberg, Anders
    et al.
    KTH, School of Computer Science and Communication (CSC), Speech, Music and Hearing, TMH, Music Acoustics.
    Schoonderwaldt, Erwin
    KTH, School of Computer Science and Communication (CSC), Speech, Music and Hearing, TMH, Music Acoustics. Hanover University, Germany .
    Hedblad, Anton
    KTH, School of Computer Science and Communication (CSC), Speech, Music and Hearing, TMH.
    Fabiani, Marco
    KTH, School of Computer Science and Communication (CSC), Speech, Music and Hearing, TMH, Music Acoustics.
    Elowsson, Anders
    KTH, School of Computer Science and Communication (CSC), Speech, Music and Hearing, TMH, Music Acoustics.
    Using listener-based perceptual features as intermediate representations in music information retrieval2014In: Journal of the Acoustical Society of America, ISSN 0001-4966, E-ISSN 1520-8524, Vol. 136, no 4, p. 1951-1963Article in journal (Refereed)
    Abstract [en]

    The notion of perceptual features is introduced for describing general music properties based on human perception. This is an attempt at rethinking the concept of features, aiming to approach the underlying human perception mechanisms. Instead of using concepts from music theory such as tones, pitches, and chords, a set of nine features describing overall properties of the music was selected. They were chosen from qualitative measures used in psychology studies and motivated from an ecological approach. The perceptual features were rated in two listening experiments using two different data sets. They were modeled both from symbolic and audio data using different sets of computational features. Ratings of emotional expression were predicted using the perceptual features. The results indicate that (1) at least some of the perceptual features are reliable estimates; (2) emotion ratings could be predicted by a small combination of perceptual features with an explained variance from 75% to 93% for the emotional dimensions activity and valence; (3) the perceptual features could only to a limited extent be modeled using existing audio features. Results clearly indicated that a small number of dedicated features were superior to a "brute force" model using a large number of general audio features.

  • 28. Galembo, A.
    et al.
    Askenfelt, Anders
    KTH, Superseded Departments, Speech Transmission and Music Acoustics.
    Cuddy, L. L.
    Russo, F. A.
    Effects of relative phases on pitch and timbre in the piano bass range2001In: Journal of the Acoustical Society of America, ISSN 0001-4966, E-ISSN 1520-8524, Vol. 110, no 3, p. 1649-1666Article in journal (Refereed)
    Abstract [en]

    Piano bass tones raise questions related to the perception of multicomponent, inharmonic tones. In this study, the influence of the relative phases among partials on pitch and timbre was investigated for synthesized bass tones with piano-like inharmonicity. Three sets of bass tones (A0 = 27.5 Hz, 100 partials, flat spectral envelope) were generated; harmonic, low inharmonic, and high inharmonic. For each set, five starting phase relations among partials were applied; sine phases, alternate (sine/cosine) phases, random phases, Schroeder phases, and negative Schroeder phases. The pitch and timbre of the tones were influenced markedly by the starting phases. Listening tests showed that listeners are able to discriminate between tones having different starting phase relations, and also that the pitch could be changed by manipulating the relative phases (octave, fifth, major third). A piano-like inharmonicity gives a characteristic randomizing effect of the phase relations over time in tones starting with nonrandom phase relations. A measure of the regularity of the phase differences between adjacent partials is suggested for quantifying this randomization process. The observed phase effects might be of importance in synthesizing, recording, and reproducing piano music.

  • 29. Goebl, W.
    et al.
    Bresin, Roberto
    KTH, Superseded Departments, Speech Transmission and Music Acoustics.
    Measurement and reproduction accuracy of computer-controlled grand pianos2003In: Journal of the Acoustical Society of America, ISSN 0001-4966, E-ISSN 1520-8524, Vol. 114, no 4, p. 2273-2283Article in journal (Refereed)
    Abstract [en]

    The recording and reproducing capabilities of a Yamaha Disklavier grand piano and a Bosendorfer SE290 computer-controlled grand piano were tested, with the goal of examining their reliability for performance research. An experimental setup consisting of accelerometers and a calibrated microphone was used to capture key and hammer movements, as well as the acoustic signal. Five selected keys were played by pianists with two types of touch (staccato and legato). Timing and dynamic differences between the original performance, the corresponding MIDI file recorded by the computer-controlled pianos, and its reproduction were analyzed. The two devices performed quite differently with respect to timing and dynamic accuracy. The Disklavier's onset capturing was slightly more precise (+/-10 ms) than its reproduction (-20 to +30 ms); the Bosendorfer performed generally better, but its timing accuracy was slightly less precise for recording (-10 to 3 ms) than for reproduction (+/-2 ms). Both devices exhibited a systematic (linear) error in recording over time. In the dynamic dimension, the Bosendorfer showed higher consistency over the whole dynamic range, while the Disklavier performed well only in a wide middle range. Neither device was able to capture or reproduce different types of touch.

  • 30. Goebl, W.
    et al.
    Bresin, Roberto
    KTH, School of Computer Science and Communication (CSC), Speech, Music and Hearing, TMH, Music Acoustics.
    Galembo, A.
    Touch and temporal behavior of grand piano actions2005In: Journal of the Acoustical Society of America, ISSN 0001-4966, E-ISSN 1520-8524, Vol. 118, no 2, p. 1154-1165Article in journal (Refereed)
    Abstract [en]

    This study investigated the temporal behavior of grand piano actions from different manufacturers under different touch conditions and dynamic levels. An experimental setup consisting of accelerometers and a calibrated microphone was used to capture key and hammer movements, as well as the sound signal. Five selected keys were played by pianists with two types of touch (pressed touch versus struck touch) over the entire dynamic range. Discrete measurements were extracted from the accelerometer data for each of the over 2300 recorded tones (e.g., finger-key, hammer-string, and key bottom contact times, maximum hammer velocity). Travel times of the hammer (from finger-key to hammer-string) as a function of maximum hammer velocity varied clearly between the two types of touch, but only slightly between pianos. A travel time approximation used in earlier work [Goebl W., (2001). J. Acoust. Soc. Am. 110, 563-572] derived from a computer-controlled piano was verified. Constant temporal behavior over type of touch and low compression properties of the parts of the action (reflected in key bottom contact times) were hypothesized to be indicators for instrumental quality.

  • 31. Goebl, Werner
    et al.
    Bresin, Roberto
    KTH, School of Computer Science and Communication (CSC), Speech, Music and Hearing, TMH, Music Acoustics. KTH, School of Computer Science and Communication (CSC), Media Technology and Interaction Design, MID.
    Fujinaga, Ichiro
    Perception of touch quality in piano tones2014In: Journal of the Acoustical Society of America, ISSN 0001-4966, E-ISSN 1520-8524, Vol. 136, no 5, p. 2839-2850Article in journal (Refereed)
    Abstract [en]

    Both timbre and dynamics of isolated piano tones are determined exclusively by the speed with which the hammer hits the strings. This physical view has been challenged by pianists who emphasize the importance of the way the keyboard is touched. This article presents empirical evidence from two perception experiments showing that touch-dependent sound components make sounds with identical hammer velocities but produced with different touch forms clearly distinguishable. The first experiment focused on finger-key sounds: musicians could identify pressed and struck touches. When the finger-key sounds were removed from the sounds, the effect vanished, suggest- ing that these sounds were the primary identification cue. The second experiment looked at key- keyframe sounds that occur when the key reaches key-bottom. Key-bottom impact was identified from key motion measured by a computer-controlled piano. Musicians were able to discriminate between piano tones that contain a key-bottom sound from those that do not. However, this effect might be attributable to sounds associated with the mechanical components of the piano action. In addition to the demonstrated acoustical effects of different touch forms, visual and tactile modalities may play important roles during piano performance that influence the production and perception of musical expression on the piano.

  • 32.
    Granqvist, Svante
    et al.
    KTH, Superseded Departments, Speech, Music and Hearing.
    Hammarberg, Britta
    The correlogram: A visual display of periodicity2003In: Journal of the Acoustical Society of America, ISSN 0001-4966, E-ISSN 1520-8524, Vol. 114, no 5, p. 2934-2945Article in journal (Refereed)
    Abstract [en]

    Fundamental frequency (F-0) extraction is often used in voice quality analysis'. In pathological voices with a high degree of instability in F-0, it is common for F-0 extraction algorithms to fail. In such cases, the faulty F-0 values might spoil the possibilities for further data analysis. This paper presents the correlogram, a new method of displaying periodicity. The correlogram is based on the waveform-matching techniques often used in F-0 extraction programs, but with no mechanism to select an actual F-0 value. Instead, several candidates for F-0 are shown as dark bands. The result is presented as a 3D plot with time on the x axis, correlation delay inverted to frequency on the y axis, and correlation on the z axis. The z axis is represented in a gray scale as in a spectrogram. Delays corresponding to integer multiples, of the period time will receive high correlation, thus resulting in candidates at F-0, F-0/2, F-0/3, etc. While the correlogram, adds little to F-0 analysis of normal voices, it is useful for analysis of pathological voices since it illustrates the full. complexity of the periodicity in the voice signal. Also, in combination with manual tracing, the correlogram can be used for semimanual F-0 extraction. If so, F-0 extraction can be performed on many voices that cause problems for conventional F-0 extractors. To demonstrate the properties of the method it is applied to synthetic and natural voices, among them six pathological voices, which are characterized by roughness, vocal fry, gratings/scrape, hypofunctional breathiness and voice breaks, or combinations of these.

  • 33.
    Granqvist, Svante
    et al.
    KTH, Superseded Departments, Speech, Music and Hearing.
    Lindestad, Per-Åke
    A method of applying Fourier analysis to high-speed laryngoscopy2001In: Journal of the Acoustical Society of America, ISSN 0001-4966, E-ISSN 1520-8524, Vol. 110, no 6, p. 3193-3197Article in journal (Refereed)
    Abstract [en]

    A new method for analysis of digital high-speed recordings of vocal-fold vibrations is presented. The method is based on the extraction of light-intensity time sequences from consecutive images, which in turn are Fourier transformed. The spectra thus acquired can be displayed in four different modes, each having its own benefits. When applied to the larynx, the method visualizes oscillations in the entire laryngeal area, not merely the glottal region. The method was applied to two laryngoscopic high-speed image sequences. Among these examples, covibrations in the ventricular folds and in the mucosa covering the arytenoid cartilages were found. In some cases the covibrations occurred at other frequencies than those of the glottis.

  • 34.
    Granqvist, Svante
    et al.
    KTH, School of Computer Science and Communication (CSC), Speech, Music and Hearing, TMH, Speech Communication and Technology.
    Sundberg, Johan
    KTH, School of Computer Science and Communication (CSC), Speech, Music and Hearing, TMH.
    Lundberg, J. O.
    Weitzberg, E.
    Paranasal sinus ventilation by humming2006In: Journal of the Acoustical Society of America, ISSN 0001-4966, E-ISSN 1520-8524, Vol. 119, no 5, p. 2611-2617Article in journal (Refereed)
    Abstract [en]

    The gas nitric oxide (NO) is generated in the human paranasal sinuses and can be measured in nasally exhaled air. During humming, a marked increase in exhaled NO content has been observed. The acoustic phenomenon responsible for this evacuation of NO gas from the sinuses was analyzed. A tube model was constructed with a syringe containing NO gas attached radially. This tube was excited with an air stream modulated by a sine wave. Increased evacuation was observed whenever the syringe was not located at a pressure node of the exciting sine wave. A computer model of the system showed a good matching of observed pressure versus frequency data in the syringe resonator. The results thus suggest that the alternating pressure in the nasal cavity forces the air plug in the ostium of the paranasal sinus resonators to vibrate, thus expelling from the cavity NO gas, which is transported to free air by the exhalatory air stream.

  • 35.
    Grell, Anke
    et al.
    KTH, School of Computer Science and Communication (CSC), Speech, Music and Hearing, TMH.
    Sundberg, Johan
    KTH, School of Computer Science and Communication (CSC), Speech, Music and Hearing, TMH.
    Ternström, Sten
    KTH, School of Computer Science and Communication (CSC), Speech, Music and Hearing, TMH, Music Acoustics.
    Ptok, Martin
    Altenmueller, Eckart
    Rapid pitch correction in choir singers2009In: Journal of the Acoustical Society of America, ISSN 0001-4966, E-ISSN 1520-8524, Vol. 126, no 1, p. 407-413Article in journal (Refereed)
    Abstract [en]

    Highly and moderately skilled choral singers listened to a perfect fifth reference, with the instruction to complement the fifth such that a major triad resulted. The fifth was suddenly and unexpectedly shifted in pitch, and the singers' task was to shift the fundamental frequency of the sung tone accordingly. The F0 curves during the transitions often showed two phases, an initial quick and large change followed by a slower and smaller change, apparently intended to fine-tune voice F0 to complement the fifth. Anesthetizing the vocal folds of moderately skilled singers tended to delay the reaction. The means of the response times varied in the range 197- 259 ms depending on direction and size of the pitch shifts, as well as on skill and anesthetization.

  • 36.
    Gudmarsson, Anders
    et al.
    KTH, School of Architecture and the Built Environment (ABE), Transport Science, Highway and Railway Engineering.
    Ryden, N.
    Birgisson, Björn
    KTH, School of Architecture and the Built Environment (ABE), Transport Science, Highway and Railway Engineering.
    Application of Resonant Acoustic Spectoscopy to Beam Shaped Asphalt Concrete Samples2010In: Journal of the Acoustical Society of America, ISSN 0001-4966, E-ISSN 1520-8524, Vol. 128, no 4, p. 2453-2453Article in journal (Refereed)
    Abstract [en]

    The dynamic modulus of asphalt concrete is a key parameter needed in modern pavement design and management. Traditional laboratory tests based on cyclic loading (0.1–25 Hz) at different testing temperatures are time consuming and require expensive equipment. There is therefore a need for more efficient non‐destructive methods to determine the dynamic modulus of asphalt concrete. This study applies resonant acoustic spectroscopy (RAS) to beam shaped asphalt concrete samples. Multiple modes of vibration are measured at each testing temperature using a miniature accelerometer and a small steel sphere as impact source. The complex modulus from each resonant frequency is calculated using the Rayleigh–Ritz method. The heterogeneous and viscoelastic nature of asphalt concrete presents challenges to the application of conventional RAS. The number of measurable modes decreases with increasing test temperature. In an attempt to extend the usable frequency and temperature range measured, transfer functions are inverted using the finite element method along with a frequency dependent complex modulus. Initial results indicate that RAS can be an efficient method for the prediction of the high‐frequency part of the asphalt concrete dynamic modulus mastercurve.

  • 37.
    Gudmarsson, Anders
    et al.
    KTH, School of Architecture and the Built Environment (ABE), Transport Science, Highway and Railway Engineering.
    Rydén, Nils
    KTH, School of Architecture and the Built Environment (ABE), Transport Science, Highway and Railway Engineering.
    Birgisson, Björn
    KTH, School of Architecture and the Built Environment (ABE), Transport Science, Highway and Railway Engineering.
    Characterizing the low strain complex modulus of asphalt concrete specimens through optimization of frequency response functions2012In: Journal of the Acoustical Society of America, ISSN 0001-4966, E-ISSN 1520-8524, Vol. 132, no 4, p. 2304-2312Article in journal (Refereed)
    Abstract [en]

    Measured and finite element simulated frequency response functions are used to characterize the low strain (similar to 10(-7)) complex moduli of an asphalt concrete specimen. The frequency response functions of the specimen are measured at different temperatures by using an instrumented hammer to apply a load and an accelerometer to measure the dynamic response. Theoretical frequency response functions are determined by modeling the specimen as a three-dimensional (3D) linear isotropic viscoelastic material in a finite element program. The complex moduli are characterized by optimizing the theoretical frequency response functions against the measured ones. The method is shown to provide a good fit between the frequency response functions, giving an estimation of the complex modulus between minimum 500 Hz and maximum 18 vertical bar 000 Hz depending on the temperature. Furthermore, the optimization method is shown to give a good estimation of the complex modulus master curve.

  • 38. Guettler, K.
    et al.
    Askenfelt, Anders
    KTH, School of Computer Science and Communication (CSC), Speech, Music and Hearing, TMH, Music Acoustics.
    Buen, A.
    Double basses on the stage floor: Tuning fork–table top effect or not?2012In: Journal of the Acoustical Society of America, ISSN 0001-4966, E-ISSN 1520-8524, Vol. 131, no 1, p. 795-806Article in journal (Refereed)
    Abstract [en]

    The question whether or not double basses can benefit from a compliant and radiating stage floor in the low end of their tonal register, similar to the well-known tuning fork–tabletop effect, was examined through field experiments in five concert halls. The topic comprises several aspects: (1) How well the mechanical impedances of double basses and the stage floor match, (2) amount of vibration velocity transmitted to the floor through the end pin of the bass, and (3) radiation efficiency of point-excited bending waves in the stage floor far below the coincidence frequency. Each aspect represents a prerequisite for the tuning fork–tabletop effect to take place. The input impedance at the end pin was measured for three representative double basses. The stage floors of five orchestra halls were measured with respect input impedance and damping, while sound radiation to the audience area was measured for two of them. In Lindeman Hall, Oslo, all conditions for the tuning fork–tabletop effect to take place were clearly met. The contribution from the stage-floor radiation to the sound pressure level in the audience area was found to be about 5 dB between 40 and 60 Hz, and even higher between 30 and 40 Hz.

  • 39. Gustafsson, M.
    et al.
    He, Sailing
    KTH, Superseded Departments, Electromagnetic Theory.
    An optimization approach to multi-dimensional time domain acoustic inverse problems2000In: Journal of the Acoustical Society of America, ISSN 0001-4966, E-ISSN 1520-8524, Vol. 108, no 4, p. 1548-1556Article in journal (Refereed)
  • 40.
    Heldner, Mattias
    KTH, School of Computer Science and Communication (CSC), Speech, Music and Hearing, TMH, Speech Communication and Technology.
    Detection thresholds for gaps, overlaps, and no-gap-no-overlaps2011In: Journal of the Acoustical Society of America, ISSN 0001-4966, E-ISSN 1520-8524, Vol. 130, no 1, p. 508-513Article in journal (Refereed)
    Abstract [en]

    Detection thresholds for gaps and overlaps, that is acoustic and perceived silences and stretches of overlapping speech in speaker changes, were determined. Subliminal gaps and overlaps were categorized as no-gap-no-overlaps. The established gap and overlap detection thresholds both corresponded to the duration of a long vowel, or about 120 ms. These detection thresholds are valuable for mapping the perceptual speaker change categories gaps, overlaps, and no-gap-no-overlaps into the acoustic domain. Furthermore, the detection thresholds allow generation and understanding of gaps, overlaps, and no-gap-no-overlaps in human-like spoken dialogue systems.

  • 41. Heo, Yong-Ho
    et al.
    Ih, Jeong-Guon
    Bodén, Hans
    KTH, School of Engineering Sciences (SCI), Aeronautical and Vehicle Engineering, Marcus Wallenberg Laboratory MWL.
    Acoustic source identification of an axial fan in a duct considering the rotation effect2016In: Journal of the Acoustical Society of America, ISSN 0001-4966, E-ISSN 1520-8524, Vol. 140, no 1, p. 145-156Article in journal (Refereed)
    Abstract [en]

    For developing the quiet axial fans, the spatial distribution of acoustic source parameters over the source plane provides essential information. In this study, the previously suggested source identification technique by authors is newly applied to an axial fan. To obtain the acoustic source parameters in a duct, one should overcome many technical difficulties related with: the turbulent flow, high order modes, rotating sources, inverse estimation. Measurements are conducted with several arrays of flush mounted microphones deployed on the periphery of the duct wall. A reference trigger signal obtained from the rotating blade is used to suppress the effect of turbulent flow in the measured pressure spectra with a reduction of about 25 dB in the present work. The maximum error between measurement and estimation is generally <-20 dB in the measurement plane in the very vicinity to the source. The visualized source images clearly indicate the locations and the strengths of main contributors to the radiated sound, e.g., for the inlet of the axial fan, the tip clearance between fan blades and shroud wall.

  • 42. Herbst, Christian T.
    et al.
    Ternström, Sten
    KTH, School of Computer Science and Communication (CSC), Speech, Music and Hearing, TMH, Music Acoustics.
    Svec, Jan G.
    Investigation of four distinct glottal configurations in classical singing-A pilot study2009In: Journal of the Acoustical Society of America, ISSN 0001-4966, E-ISSN 1520-8524, Vol. 125, no 3, p. EL104-EL109Article in journal (Refereed)
    Abstract [en]

    This study investigates four qualities of singing voice in a classically trained baritone: "naive falsetto," "countertenor falsetto," "lyrical chest" and "full chest." Laryngeal configuration and vocal fold behavior in these qualities were studied using laryngeal videostroboscopy, videokymography, electroglottography, and sound spectrography. The data suggest that the four voice qualities were produced by independently manipulating mainly two laryngeal parameters: (1) the adduction of the arytenoid cartilages and (2) the thickening of the vocal folds. An independent control of the posterior adductory muscles versus the vocalis muscle is considered to be the physiological basis for achieving these singing voice qualities.

  • 43.
    Häggblad, Jon
    et al.
    KTH, School of Computer Science and Communication (CSC), Numerical Analysis, NA (closed 2012-06-30).
    Engquist, Björn
    University of Texas.
    Consistent modeling of boundaries in acoustic finite-difference time-domain simulations2012In: Journal of the Acoustical Society of America, ISSN 0001-4966, E-ISSN 1520-8524, Vol. 132, no 3, p. 1303-1310Article in journal (Refereed)
    Abstract [en]

    The finite-difference time-domain method is one of the most popular for wave propagation in the time domain. One of its advantages is the use of a structured staggered grid, which makes it simple and efficient on modern computer architectures. A drawback however is the difficulty in approximating oblique boundaries, having to resort to staircase approximations.  In many scattering problems this means that the grid resolution required to obtain an accurate solution is much higher than what is dictated by propagation in a homogeneous material.  In this paper zero boundary data is considered, first for the velocity and then the pressure. These two forms of boundary conditions model perfectly rigid and pressure-release boundaries, respectively.  A simple and efficient method to consistently model curved rigid boundaries in two dimensions was developed in [A.-K. Tornberg and B. Engquist, J. Comput. Phys. 227, 6922--6943 (2008)].  Here this treatment is generalized to three dimensions.  Based on the approach of this method, a technique to model pressure-release surfaces with second order accuracy and without additional restriction on the timestep is also introduced.  The structure of the standard method is preserved, making it easy to use in existing solvers.  The effectiveness is demonstrated in several numerical tests.

  • 44.
    Kari, Leif
    KTH, Superseded Departments, Vehicle Engineering.
    On the dynamic stiffness of preloaded vibration isolators in the audible frequency range: Modeling and experiments2003In: Journal of the Acoustical Society of America, ISSN 0001-4966, E-ISSN 1520-8524, Vol. 113, no 4, p. 1909-1921Article in journal (Refereed)
    Abstract [en]

    The nonlinear, preload-dependent dynamic stiffness of a cylindrical vibration isolator is examined via measurements and modeling within an audible frequency range covering 50 to 1000 Hz at various preloads. The stiffness is found to depend strongly on frequency-resulting in peaks and troughs, and on preload-particularly above 500 Hz. The problems of simultaneously modeling the rubber prestrain dependence and its audible short-term response are removed by adopting a nearly incompressible material model, being elastic in dilatation while displaying viscoelasticity in deviation. The latter exhibits a time strain separable relaxation tensor with a single function embodying its time dependence. This function is based on a continuous fractional order derivative model, the main advantage being the minimum number of parameters required to successfully model the rubber properties over a broad structure-borne sound frequency domain, while embodying a continuous distribution of relaxation time. The weak formulations corresponding to the stiffness problem are solved by an updated Lagrangian nonlinear finite-element procedure. The model and measurement results agree strikingly well with static and dynamic measurements throughout the whole frequency domain for the examined preloads.

  • 45.
    Karlsson, Mikael
    et al.
    KTH, School of Engineering Sciences (SCI), Aeronautical and Vehicle Engineering, MWL Flow acoustics.
    Glav, Ragnar
    KTH, School of Engineering Sciences (SCI), Aeronautical and Vehicle Engineering, Marcus Wallenberg Laboratory MWL.
    Åbom, Mats
    KTH, School of Engineering Sciences (SCI), Centres, Linné Flow Center, FLOW.
    The Herschel-Quincke tube: The attenuation conditions and their sensitivity to mean flow2008In: Journal of the Acoustical Society of America, ISSN 0001-4966, E-ISSN 1520-8524, Vol. 124, no 2, p. 723-732Article in journal (Refereed)
    Abstract [en]

    The classic Herschel-Quincke tube is a parallel connection of two ducts yielding multiple noise attenuation maxima via destructive interference. This problem has been discussed to different degrees by a number of authors over the years. This study returns to the basics of the system for the purpose of furthering the understanding of the conditions necessary for noise attenuation and especially their sensitivity to mean flow. First, the transmission loss for an N-duct system with mean flow and arbitrary conditions of state in the different ducts is derived. Next, the two types of conditions yielding the attenuation maxima are studied. In addition to a discussion of the underlying physics, generic expressions for frequencies at which maximum attenuation occur are presented. Experiments without mean flow generally show good agreement with theory based on straight duct elements. However, more detailed models may be required for accurate simulations in the presence of mean flow. A simple model compensating for the losses associated with bends is shown to improve the results significantly for the geometry studied.

  • 46.
    Kierkegaard, Axel
    et al.
    KTH, School of Engineering Sciences (SCI), Aeronautical and Vehicle Engineering, Marcus Wallenberg Laboratory MWL.
    Boij, Susann
    KTH, School of Engineering Sciences (SCI), Aeronautical and Vehicle Engineering, Marcus Wallenberg Laboratory MWL. KTH, School of Engineering Sciences (SCI), Centres, VinnExcellence Center for ECO2 Vehicle design.
    Efraimsson, Gunilla
    KTH, School of Engineering Sciences (SCI), Aeronautical and Vehicle Engineering, Aeroacoustics. KTH, School of Engineering Sciences (SCI), Centres, Linné Flow Center, FLOW.
    A frequency domain linearized Navier-Stokes equations approach to acoustic propagation in flow ducts with sharp edges2010In: Journal of the Acoustical Society of America, ISSN 0001-4966, E-ISSN 1520-8524, Vol. 127, no 2, p. 710-719Article in journal (Refereed)
    Abstract [en]

    Acoustic wave propagation in flow ducts is commonly modeled with time-domain non-linear Navier-Stokes equation methodologies. To reduce computational effort, investigations of a linearized approach in frequency domain are carried out. Calculations of sound wave propagation in a straight duct are presented with an orifice plate and a mean flow present. Results of transmission and reflections at the orifice are presented on a two-port scattering matrix form and are compared to measurements with good agreement. The wave propagation is modeled with a frequency domain linearized Navier-Stokes equation methodology. This methodology is found to be efficient for cases where the acoustic field does not alter the mean flow field, i.e., when whistling does not occur.

  • 47.
    Koniaris, Christos
    et al.
    KTH, School of Electrical Engineering (EES), Sound and Image Processing.
    Kuropatwinski, Marcin
    KTH, School of Electrical Engineering (EES), Sound and Image Processing.
    Kleijn, Bastiaan
    KTH, School of Electrical Engineering (EES), Sound and Image Processing.
    Auditory-model based robust feature selection for speech recognition2010In: Journal of the Acoustical Society of America, ISSN 0001-4966, E-ISSN 1520-8524, Vol. 127, no 2, p. EL73-EL79Article in journal (Refereed)
    Abstract [en]

     It is shown that robust dimension-reduction of a feature set for speech recognition can be based on a model of the human auditory system. Whereas conventional methods optimize classification performance, the proposed method exploits knowledge implicit in the auditory periphery, inheriting its robustness. Features are selected to maximize the similarity of the Euclidean geometry of the feature domain and the perceptual domain. Recognition experiments using mel-frequency cepstral coefficients (MFCCs) confirm the effectiveness of the approach, which does not require labeled training data. For noisy data the method outperforms commonly used discriminant-analysis based dimension-reduction methods that rely on labeling. The results indicate that selecting MFCCs in their natural order results in subsets with good performance.

  • 48. Lehtonen, Heidi-Maria
    et al.
    Askenfelt, Anders
    KTH, School of Computer Science and Communication (CSC), Speech, Music and Hearing, TMH, Music Acoustics.
    Valimaki, Vesa
    Analysis of the part-pedaling effect in the piano2009In: Journal of the Acoustical Society of America, ISSN 0001-4966, E-ISSN 1520-8524, Vol. 126, no 2, p. EL49-EL54Article in journal (Refereed)
    Abstract [en]

    This letter reports basic acoustic phenomena related to part-pedaling in the piano. With part-pedaling, the piano tone can be divided into three distinct time intervals: initial free vibration, damper-string interaction, and final free vibration. Varying the distance of the damper from the string, the acoustic signal and the damper acceleration were measured for several piano tones. During the damper-string interaction, the piano tone decay is rapid and the timbre of the tone is affected by the nonlinear amplitude limitation of the string motion. During the final free decay, the string continues to vibrate freely with a lower decay rate.

  • 49.
    Lind Nordgren, Eleonora
    et al.
    KTH, School of Engineering Sciences (SCI), Aeronautical and Vehicle Engineering, Marcus Wallenberg Laboratory MWL. KTH, School of Engineering Sciences (SCI), Centres, VinnExcellence Center for ECO2 Vehicle design.
    Göransson, Peter
    KTH, School of Engineering Sciences (SCI), Aeronautical and Vehicle Engineering, Marcus Wallenberg Laboratory MWL. KTH, School of Engineering Sciences (SCI), Centres, VinnExcellence Center for ECO2 Vehicle design.
    Deü, Jean-Francois
    National Conservatory of Arts and Crafts, Laboratoire de Mécanique des Structures et des Systémes Couplés (LMSSC), Conservatoire National des Arts et Metiérs, France.
    Dazel, Olivier
    University of Maine, Laboratoire d'Acoustique de l'Université du Maine, France.
    Vibroacoustic response sensitivity due to relative alignment of two anisotropic poro-elastic layers2013In: Journal of the Acoustical Society of America, ISSN 0001-4966, E-ISSN 1520-8524, Vol. 133, no 5, p. EL426-EL430Article in journal (Refereed)
    Abstract [en]

    The effects of relative alignment of two different types of anisotropic open cell porous materials are investigated in terms of the acoustic response of a multi-layered configuration. Numerical experiments, where gradient based optimization techniques were used, are conducted to find possible extremal values. It is shown that, depending on the degree of anisotropy of the porous material properties, their angular orientations have a significant and frequency dependent influence on the measured response. The results highlight the importance of further advancing the knowledge of anisotropic porous material behavior.

  • 50.
    Liu, Hao
    et al.
    KTH, School of Engineering Sciences (SCI), Aeronautical and Vehicle Engineering, Marcus Wallenberg Laboratory MWL.
    Finnveden, Svante
    KTH, School of Engineering Sciences (SCI), Aeronautical and Vehicle Engineering, Marcus Wallenberg Laboratory MWL.
    Barbagallo, Mathias
    KTH, School of Engineering Sciences (SCI), Aeronautical and Vehicle Engineering, Marcus Wallenberg Laboratory MWL.
    Lopez Arteaga, Ines
    KTH, School of Engineering Sciences (SCI), Aeronautical and Vehicle Engineering, Marcus Wallenberg Laboratory MWL.
    Wave propagation in sandwich panels with a poroelastic core2014In: Journal of the Acoustical Society of America, ISSN 0001-4966, E-ISSN 1520-8524, Vol. 135, no 5, p. 2683-2693Article in journal (Refereed)
    Abstract [en]

    Wave propagation in sandwich panels with a poroelastic core, which is modeled by Biot's theory, is investigated using the waveguide finite element method. A waveguide poroelastic element is developed based on a displacement-pressure weak form. The dispersion curves of the sandwich panel are first identified as propagating or evanescent waves by varying the damping in the panel, and wave characteristics are analyzed by examining their motions. The energy distributions are calculated to identify the dominant motions. Simplified analytical models are also devised to show the main physics of the corresponding waves. This wave propagation analysis provides insight into the vibro-acoustic behavior of sandwich panels lined with elastic porous materials.

12 1 - 50 of 98
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