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  • 101. Tamadapu, Ganesh
    et al.
    Grishenkov, Dmitry
    KTH, Skolan för teknik och hälsa (STH), Medicinsk teknik, Medicinsk bildteknik.
    Eriksson, Anders
    Modeling and parametric investigation of thick encapsulated microbubble's nonspherical oscillations2016Ingår i: Journal of the Acoustical Society of America, ISSN 0001-4966, E-ISSN 1520-8524, Vol. 140, nr 5, s. 3884-3895Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    Numerous studies have been carried out in the past few decades to investigate the radial oscillations of encapsulated microbubbles (MBs). Nonspherical oscillations also have gained attention, being unavoidable in actual applications of these bubbles. The present paper is intended to describe the nature of resonance trends of such spherical and nonspherical modes of a thick encapsulated MB filled with air and suspended in water. The shell material is assumed to be linear viscoelastic and quasi-incompressible. The considered isotropic and spherically isotropic material parametric range is limited to thick polymer shelled MBs. For the case of an isotropic material, shell viscosity has a major influence on the fundamental modes with meridional wave number n = 0, 4, especially for thicker bubbles, unlike for the case of the spherically isotropic material case considered, where the viscosity has very little influence. For most of the parametric range, n = 2, 3 modes are underdamped and their frequency is found to be lower than the n = 0, 4 modes, for both material cases. An interesting case is found for a spherically isotropic quasiincompressible material case, where the first few nonspherical mode resonances are very close to radial mode resonance frequency.

  • 102.
    Temiz, Muttalip Askin
    et al.
    Eindhoven University of Technology, Department of Mechanical Engineering, Dynamics and Control, The Netherlands.
    Arteaga, Ines Lopez
    Eindhoven University of Technology, Department of Mechanical Engineering, Dynamics and Control, The Netherlands.
    Efraimsson, Gunilla
    KTH, Skolan för teknikvetenskap (SCI), Farkost och flyg. KTH, Skolan för teknikvetenskap (SCI), Centra, VinnExcellence Center for ECO2 Vehicle design.
    Åbom, Mats
    KTH, Skolan för teknikvetenskap (SCI), Centra, Linné Flow Center, FLOW. KTH, Skolan för teknikvetenskap (SCI), Farkost och flyg, MWL Marcus Wallenberg Laboratoriet.
    Hirschberg, Avraham
    Eindhoven University of Technology, Department of Applied Physics, Gas Dynamics and Aero-Acoustics, The Netherlands.
    The influence of edge geometry on end-correction coefficients in micro perforated plates2015Ingår i: Journal of the Acoustical Society of America, ISSN 0001-4966, E-ISSN 1520-8524, Vol. 138, nr 6, s. 3668-3677Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    Global expressions are proposed for end-correction coefficients in micro perforated plates (MPPs) using non-dimensional parameters. MPPs are sound absorbers with small perforation diameters such that the Stokes boundary layers fill up almost the entire perforation. Sound absorption does not only occur within the perforation, but also takes place just outside of it. The latter contribution plus the outside inertia effect on the transfer impedance of the MPP are referred to as end-corrections. In order to determine them, an analytical solution employing the very thin Stokes layer assumption has been derived. However, this assumption requires empirical coefficients in the end-corrections for accurate results. To explore the effects of various parameters a numerical model is used. This model is verified with open-end reflection coefficient measurements. The most prominent result from this study is that compared to plate thickness, the ratio of perforation diameter to Stokes layer thickness (Shear number) and edge geometry affect the end-correction coefficients more significantly. The effect of plate thickness can be neglected for practical purposes, therefore, expressions for the end-corrections in terms of Shear number and edge geometry are provided. The relative error of these expressions is <3% compared to the numerical results. 

  • 103.
    Ternström, Sten
    KTH, Skolan för elektroteknik och datavetenskap (EECS), Tal, musik och hörsel, TMH.
    Normalized time-domain parameters for electroglottographic waveforms2019Ingår i: Journal of the Acoustical Society of America, ISSN 0001-4966, E-ISSN 1520-8524, Vol. 146, nr 1, s. EL65-EL70, artikel-id 1.5117174Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    The electroglottographic waveform is of interest for characterizing phonation non-invasively. Existing parameterizations tend to give disparate results because they rely on somewhat arbitrary thresholds and/or contacting events. It is shown that neither are needed for formulating a normalized contact quotient and a normalized peak derivative. A heuristic combination of the two resolves also the ambiguity of a moderate contact quotient, with regard to vocal fold contacting being firm versus weak or absent. As preliminaries, schemes for electroglottography signal preconditioning and time-domain period detection are described that improve somewhat on similar methods. The algorithms are simple and compute quickly.

  • 104.
    Ternström, Sten
    KTH, Tidigare Institutioner, Tal, musik och hörsel.
    Preferred self-to-other ratios in choir singing1999Ingår i: Journal of the Acoustical Society of America, ISSN 0001-4966, E-ISSN 1520-8524, Vol. 105, nr 6, s. 3563-3574Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    Choir singers need to hear their own voice in an adequate self-to-other ratio (SOR) over the rest ofthe choir. Knowing singers’ preferences for SOR could facilitate the design of stages and of choral formations. In an experiment to study the preferred SOR, subjects sang sustained vowels together with synthesized choir sounds, whose loudness tracked that of their own voice. They could control the SOR simply by changing their distance to the microphone. At the most comfortable location, the SOR was measured. Experimental factors included unison and four-part tasks, three vowels and two levels of phonation frequency. The same experiment was run four times, using sopranos, altos, tenors, and basses, with stimulus tones adapted for each category. The preferred self-to-other ratios were found to be similar to SORs measured previously in actual performance, if a little higher. Preferences were quite narrow, typically +/-2 dB for each singer, but very different from singer to singer, with intrasubject means ranging from -1 to +15 dB. There was no significant difference between the unison and the four-part tasks, although this might have been caused by systematic differences in the stimulus sounds. Some effects of phonation frequency and vowel were significant, but interdependent and difficult to interpret. The results and their relevance to live choir singing are discussed.

  • 105.
    Ternström, Sten
    et al.
    KTH, Skolan för datavetenskap och kommunikation (CSC), Tal, musik och hörsel, TMH, Musikakustik.
    Bohman, M.
    Södersten, M.
    Loud speech over noise: Some spectral attributes, with gender differences2006Ingår i: Journal of the Acoustical Society of America, ISSN 0001-4966, E-ISSN 1520-8524, Vol. 119, nr 3, s. 1648-1665Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    In seeking an acoustic description of overloaded voice, simulated environmental noise was used to elicit loud speech. A total of 23 adults, 12 females and 11 males, read six passages of 90 s duration, over realistic noise presented over loudspeakers. The noise was canceled out, exposing the speech signal to analysis. Spectrum balance (SB) was defined as the level of the 2-6 kHz band relative to the 0.1-1 kHz band. SB averaged across many similar vowel segments became less negative with increasing sound pressure level (SPL), as described in the literature, but only at moderate SPL. At high SPL, SB exhibited a personal saturation point, above which the high-band level no longer increased faster than the overall SPL, or even stopped increasing altogether, on average at 90.3 dB WO cm) for females and 95.5 dB for males. Saturation occurred 6-8 dB; below the personal maximum SPL, regardless of gender. The loudest productions were often characterized by a relative increase in low-frequency energy, apparently in a sharpened first formant. This suggests a change of vocal strategy when the high spectrum can rise no further. The progression of SB with SPL was characteristically different for individual subjects.

  • 106.
    Ternström, Sten
    et al.
    KTH, Skolan för datavetenskap och kommunikation (CSC), Tal, musik och hörsel, TMH, Musikakustik.
    Cabrera, D.
    Davis, P.
    Self-to-other ratios measured in an opera chorus in performance2005Ingår i: Journal of the Acoustical Society of America, ISSN 0001-4966, E-ISSN 1520-8524, Vol. 118, nr 6, s. 3903-3911Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    Four volunteer members of the chorus of Opera Australia, representing four different voice categories, wore binaural pairs of wireless microphones during a penultimate dress rehearsal on the Opera Theater stage of the Sydney Opera House. From the recordings, data were obtained oil sound levels and on the self-to-other ratios (SORs). The sound levels were comparable to those found in loud music in chamber choir performance. The average SOR ranged from +10 to +15 dB. Compared to chamber choirs in other types of room, the SOR values were high. On a separate occasion, the stage support parameters ST1 (early reflections) and ST2 (late reflections) were measured over the whole stage area. STI was about -16 dB, which is typical for opera stages, and -20 dB for ST2, which is unusually low. It is concluded that the SOR in the opera chorus depends mostly on choir formation, which is highly variable, and that an opera chorus artist generally can hear his or her own voice very well, but little of the others and of the orchestra. This was confirmed by informal listening to the recordings.

  • 107.
    Ternström, Sten
    et al.
    KTH, Tidigare Institutioner (före 2005), Talöverföring och musikakustik.
    Sundberg, Johan
    KTH, Tidigare Institutioner (före 2005), Talöverföring och musikakustik.
    Intonation precision of choir singers1988Ingår i: Journal of the Acoustical Society of America, ISSN 0001-4966, E-ISSN 1520-8524, Vol. 84, nr 1, s. 59-69Artikel i tidskrift (Refereegranskat)
  • 108. Titze, Ingo R.
    et al.
    Baken, Ronald J.
    Bozeman, Kenneth W.
    Granqvist, Svante
    KTH, Skolan för teknik och hälsa (STH), Naturvetenskap och biomedicin, Grundläggande naturvetenskap.
    Henrich, Nathalie
    Herbst, Christian T.
    Howard, David M.
    Hunter, Eric J.
    Kaelin, Dean
    Kent, Raymond D.
    Kreiman, Jody
    Kob, Malte
    Loefqvist, Anders
    McCoy, Scott
    Miller, Donald G.
    Noe, Hubert
    Scherer, Ronald C.
    Smith, John R.
    Story, Brad H.
    Svec, Jan G.
    Ternström, Sten
    KTH, Skolan för datavetenskap och kommunikation (CSC), Tal, musik och hörsel, TMH.
    Wolfe, Joe
    Toward a consensus on symbolic notation of harmonics, resonances, and formants in vocalization2015Ingår i: Journal of the Acoustical Society of America, ISSN 0001-4966, E-ISSN 1520-8524, Vol. 137, nr 5, s. 3005-3007Artikel i tidskrift (Refereegranskat)
  • 109.
    Van der Kelen, Christophe
    et al.
    KTH, Skolan för teknikvetenskap (SCI), Farkost och flyg, MWL Strukturakustik.
    Göransson, Peter
    KTH, Skolan för teknikvetenskap (SCI), Farkost och flyg, MWL Numerisk akustik.
    Identification of the full anisotropic flow resistivity tensor for multiple glass wool and melamine foam samples2013Ingår i: Journal of the Acoustical Society of America, ISSN 0001-4966, E-ISSN 1520-8524, Vol. 134, nr 6, s. 4659-4669Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    The flow resistivity tensor, which is the inverse of the viscous permeability tensor, is one of the most important material properties for the acoustic performance of porous materials used in acoustic treatments. Due to the manufacturing processes involved, these porous materials are most often geometrically anisotropic on a microscopic scale, and for demanding applications, there is a need for improved characterization methods. This paper discusses recent refinements of a method for the identification of the anisotropic flow resistivity tensor. The inverse estimation is verified for three fictitious materials with different degrees of anisotropy. Measurements are performed on nine glass wool samples and seven melamine foam samples, and the anisotropic flow resistivity tensors obtained are validated by comparison to measurements performed on uni-directional cylindrical samples, extracted from the same, previously measured cubic samples. The variability of flow resistivity in the batch of material from which the glass wool is extracted is discussed. The results for the melamine foam suggest that there is a relation between the direction of highest flow resistivity, and the rise direction of the material.

  • 110.
    Weng, Chenyang
    et al.
    KTH, Skolan för teknikvetenskap (SCI), Farkost och flyg, MWL Marcus Wallenberg Laboratoriet. KTH, Skolan för teknikvetenskap (SCI), Centra, Linné Flow Center, FLOW.
    Boij, Susann
    KTH, Skolan för teknikvetenskap (SCI), Farkost och flyg, MWL Marcus Wallenberg Laboratoriet. KTH, Skolan för teknikvetenskap (SCI), Centra, Linné Flow Center, FLOW.
    Hanifi, Ardeshir
    KTH, Skolan för teknikvetenskap (SCI), Farkost och flyg, MWL Marcus Wallenberg Laboratoriet. KTH, Skolan för teknikvetenskap (SCI), Centra, Linné Flow Center, FLOW.
    The attenuation of sound by turbulence in internal flows2013Ingår i: Journal of the Acoustical Society of America, ISSN 0001-4966, E-ISSN 1520-8524, Vol. 133, nr 6, s. 3764-3776Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    The attenuation of sound waves due to interaction with low Mach number turbulent boundary layers in internal flows (channel or pipe flow) is examined. Dynamic equations for the turbulent Reynolds stress on the sound wave are derived, and the analytical solution to the equation provides a frequency dependent eddy viscosity model. This model is used to predict the attenuation of sound propagating in fully developed turbulent pipe flow. The predictions are shown to compare well with the experimental data. The proposed dynamic equation shows that the turbulence behaves like a viscoelastic fluid in the interaction process, and that the ratio of turbulent relaxation time near the wall and the sound wave period is the parameter that controls the characteristics of the attenuation induced by the turbulent flow.

  • 111.
    Zea, Elias
    et al.
    KTH, Skolan för teknikvetenskap (SCI), Farkost och flyg, MWL Marcus Wallenberg Laboratoriet.
    Lopez Arteaga, Ines
    KTH, Skolan för teknikvetenskap (SCI), Farkost och flyg, MWL Marcus Wallenberg Laboratoriet. Eindhoven University of Technology, Department of Mechanical Engineering.
    On modified wavenumber filters for rail contribution estimations2018Ingår i: Journal of the Acoustical Society of America, ISSN 0001-4966, E-ISSN 1520-8524, Vol. 144, s. EL286-EL289Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    This brief communication exposes an overview of various wavenumber filters to separate the rail contribution to pass-by noise via the wave signature extraction method [Zea, Manzari, Squicciarini, Feng, Thompson, and Lopez Arteaga, J. Sound Vib. 409, 24–42 (2017)]. It has been found that the originally proposed filters underesti- mate the rail noise at frequencies above 1.6 kHz due to the presence of higher-order wave families that is unaccounted for. The goal of this let- ter is thus to propose and examine different filter functions that can cap- ture such waves, and to assess whether the rail contribution estimations can be improved.

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  • 112.
    Zea, Elias
    et al.
    KTH, Skolan för teknikvetenskap (SCI), Farkost och flyg, MWL Marcus Wallenberg Laboratoriet.
    Lopez Arteaga, Ines
    KTH, Skolan för teknikvetenskap (SCI), Farkost och flyg, MWL Marcus Wallenberg Laboratoriet.
    Single-layer array method to reconstruct extended sound sources facing a parallel reflector2017Ingår i: Journal of the Acoustical Society of America, ISSN 0001-4966, E-ISSN 1520-8524, Vol. 141, nr 5, s. 3984-3984Artikel i tidskrift (Övrigt vetenskapligt)
    Abstract [en]

    The accuracy of sound field reconstruction methods with single-layer microphone arrays is subject to the room or enclosure in which the measurements take place. Thus, the authors recently introduced a single-layer method that can be employed to reconstruct compact sources in the presence of a reflecting surface that is parallel to the array. Now the authors propose a method conceived for extended planar sources such as baffled plates facing a parallel reflector. The method is based on a wavenumber-domain function describing the propagation paths between the source, the reflector and the array. The free-space sound field radiated by the source is then recovered by means of a regularized inversion of the propagation function. Numerical simulations are performed in order to assess the method's performance and potential for source reconstructions. The results are promising and point towards future experimental validation.

  • 113.
    Åberg, Mats
    et al.
    KTH, Tidigare Institutioner                               , Hållfasthetslära.
    Gudmundson, Peter
    KTH, Tidigare Institutioner                               , Hållfasthetslära.
    The usage of standard finite element codes for computation of dispersion relations in materials with periodic microstructure1997Ingår i: Journal of the Acoustical Society of America, ISSN 0001-4966, E-ISSN 1520-8524, Vol. 102, nr 4, s. 2007-2013Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    A method with which standard finite element programs can be used to compute dispersion relations in periodic composites is proposed. The method is applied to two composite microstructures: a two-phase laminate and a fiber composite. The dispersion relations computed for the laminate are compared with a known analytical solution and the agreement is very good. The dispersion relations computed for the fibrous composite are compared with an existing approximate model and experimental results from the literature. The agreement between the approximate model, the experiments, and the computations is very good in the wave guide case and satisfactory for the wave reflect case.

  • 114.
    Öberg, Fredrik
    et al.
    KTH, Skolan för datavetenskap och kommunikation (CSC), Tal, musik och hörsel, TMH, Musikakustik.
    Askenfelt, Anders
    KTH, Skolan för datavetenskap och kommunikation (CSC), Tal, musik och hörsel, TMH, Musikakustik.
    Acoustical and perceptual influence of duplex stringing in grand pianos2012Ingår i: Journal of the Acoustical Society of America, ISSN 0001-4966, E-ISSN 1520-8524, Vol. 131, nr 1, s. 856-871Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    This study investigates the acoustical and perceptual influence of the string parts outside the speaking length in grand pianos (front and rear duplex strings). Acoustical measurements on a grand piano in concert condition were conducted, measuring the fundamental frequencies of all main and duplex strings in the four octaves D4-C8. Considerable deviations from the nominal harmonic relations between the rear duplex and main string frequencies, as described by the manufacturer in a patent, were observed. Generally the rear duplex strings were tuned higher than the nominal harmonic relations with average and median deviations approaching _50 cent. Single keys reached +190 and -100 cent. The spread in deviation from harmonic relations within trichords was also substantial with average and median values around 25 cent, occasionally reaching 60 cent. Contributions from both front and rear duplex strings were observed in the bridge motion and sound. The audibility of the duplex strings was studied in an ABX listening test. Complete dampening of the front duplex was clearly perceptible both for an experiment group consisting of musicians and a control group with naive subjects. The contribution from the rear duplex could also be perceived, but less pronounced.

123 101 - 114 av 114
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