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A few aspects of aircraft noise
KTH, School of Engineering Sciences (SCI), Aeronautical and Vehicle Engineering.
2007 (English)Licentiate thesis, comprehensive summary (Other scientific)
Abstract [en]

A few aspects of aircraft noise were evaluated. These were (i) methods of subjective evaluations, (ii) effects of equalization and (iii) the effects of cognitive aspects.

In the first paper, sorting algorithms were used instead of conventional paired comparison method in order to reduce the number of pairs in the evaluation of subjective judgments. The quick sorting algorithm method revealed more than 99% correlation coefficient with paired comparison method although the method used N*log(N) evaluations instead of N(N-1)/2.

In the second paper, equalization effects on perception were evaluated in two steps, first with stationary aircraft sounds and second with non-stationary aircraft sounds.

The first experiment examined the effects of stationary sound segments respect to three different angle positions of the aircrafts relative to the observer (78.7°, 90° & 101.3°), two different SNR conditions (sounds having original broadband plus tonal components versus control broadband sounds having no tonal components) and two different flight conditions (arrival and take-off). Subjects were asked to scale five perceptual attributes (loudness, annoyance, hardness, power and pitch) using Borg CR100 scale. The angle condition showed highly significant effects on annoyance and hardness. Maximal effects were found at an angle of 78.7°. The SNR revealed a significant impact on loudness, power and pitch.

The second experiment analyzed the effects of tonal components and the problem of appropriate equalization. The spectrum of the signals was modified in two steps (buzz-saw, isolated BPF tone). Further EPNL-equalization, A-, B-, C-, D- and spectral broadband equalizations were applied to the synthesized sounds. Annoyance, loudness, hardness and pitch in the isolated tone conditions showed significantly stronger effects than the buzz-conditions on the perceived judgments. The EPNL-equalization led to a lower degree of differentiation between the spectral conditions compared to B- and C-level equalization.

In the third paper, the effects of aircraft sounds on children’s cognitive performance were investigated. Impact of aircraft noise on children cognition was found significantly higher in reading comprehensions than in basic mathematics and problem solving tests. It seems children are very sensitive to the modifications in the aircraft noise but further studies are necessary to compliment such a finding.

Place, publisher, year, edition, pages
Stockholm: Farkost och flyg , 2007.
Series
TRITA-AVE, ISSN 1651-7660 ; 2007:62
Keyword [en]
paired comparison, sorting based paired comparison, sorting algorithms, mergesort, quicksort, aircraft sound synthesis, aircraft noise, sound quality, tonal effects, angle positions, flight conditions, methods of equalization, cognition
National Category
Fluid Mechanics and Acoustics
Identifiers
URN: urn:nbn:se:kth:diva-4510OAI: oai:DiVA.org:kth-4510DiVA: diva2:12615
Presentation
2007-11-01, S40, MWL, Teknikringen 8, Stockholm, 13:00
Opponent
Supervisors
Available from: 2007-10-22 Created: 2007-10-22 Last updated: 2016-12-09
List of papers
1. A quicker method of using paired comparisons for the sound quality evaluation
Open this publication in new window or tab >>A quicker method of using paired comparisons for the sound quality evaluation
2006 (English)In: EURONOISE 2006 - The 6th European Conference on Noise Control: Advanced Solutions for Noise Control, 2006Conference paper, Published paper (Refereed)
Abstract [en]

Paired Comparison Method (PCM) is widely used by the researchers for evaluating subjective judgments of various stimuli. The conventional PCM is usually used only for a limited number of stimuli (N) since the number of pairs to judge becomes N(N-1)/2 and therefore the number of pairs increases with the number of stimuli. This makes the paired comparisons method very time consuming and more demanding if the numbers of stimuli increase. A novel method is therefore developed which gives similar results as PCM but requires significantly less number of pairs for the comparisons. As a result, this new method could be used to judge a larger number of stimuli. To this end a sorting algorithm such as mergesort is used to obtain the matrix of preference, resulting in about O(N log N) pairs of comparisons. A sorting algorithm reduces the number of pair comparisons using the transitivity of earlier responses given by the subject. Such pair comparisons provide the opportunity to include a larger number of stimuli to include for the evaluation. 12 aircraft sounds were presented to the subjects using headphones. The conventional PCM gave 66 pairs of sounds to be judged by the subjects whereas the mergesort produced only 31 pairs of sounds to be judged. The study reveals the comparisons between the results of conventional PCM and the mergesort.

Keyword
Mergesort, Paired comparison, Quicksort, Sorting algorithms, Sorting based paired comparison
National Category
Fluid Mechanics and Acoustics
Identifiers
urn:nbn:se:kth:diva-7551 (URN)2-s2.0-84872500683 (Scopus ID)
Conference
6th European Conference on Noise Control: Advanced Solutions for Noise Control, EURONOISE 2006; Tampere;30 May 2006 through 1 June 2006
Note

QC 20120907

Available from: 2007-10-22 Created: 2007-10-22 Last updated: 2014-06-16Bibliographically approved
2. Quality of stationary and non-stationary aircraft sounds: the effect of tonal components and level equalization
Open this publication in new window or tab >>Quality of stationary and non-stationary aircraft sounds: the effect of tonal components and level equalization
(English)In: Acta AcusticaArticle in journal (Other academic) Submitted
National Category
Fluid Mechanics and Acoustics
Identifiers
urn:nbn:se:kth:diva-7552 (URN)
Note
QS 20120326Available from: 2007-10-22 Created: 2007-10-22 Last updated: 2014-06-16Bibliographically approved
3. Effect of aircraft noise on children’s cognitive performance
Open this publication in new window or tab >>Effect of aircraft noise on children’s cognitive performance
(English)In: Journal of Environmental Psychology, ISSN 0272-4944, E-ISSN 1522-9610Article in journal (Other academic) Submitted
National Category
Fluid Mechanics and Acoustics
Identifiers
urn:nbn:se:kth:diva-7553 (URN)
Note
QS 20120326Available from: 2007-10-22 Created: 2007-10-22 Last updated: 2017-12-14Bibliographically approved

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