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Proceedings of Meetings on Acoustics

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POMA - 163rd Meeting Acoustical Society of America/ACOUSTCS 2012 HONG KONG
Conference Location: Hong Kong Conference Date: 13 - 18 May 2012
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Noise attenuation by sonic crystal barriers made of microperforated units

Victor M. Garcia-Chocano, Suitberto Cabrera, and Jose Sanchez-Dehesa

POMA Volume 15, pp. 015001 (May 2012); (7 pages)

Online Publication Date: May 18, 2012

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This work studies the absorptive properties of periodic arrays of microperforated cylindrical shells. Structures made of cylinders 3 meters height have been constructed and their reflectance and transmittance spectra are measured in open air at normal incidence. A broadband strong attenuation is found in the low frequency region. Experimental data are supported by model simulations performed in the framework of multiple scattering. It is concluded that these structures are suitable to produce general purpose broadband noise barriers.
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43.20.Fn Scattering of acoustic waves
43.50.Fe Noise masking systems
43.55.Ti Sound-isolating structures, values of transmission coefficients
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Syllables intelligibility in relation to the autocorrelation and cepstrum model: The case of Chinese in Taiwan

Chiung Yao Chen

POMA Volume 15, pp. 015002 (June 2012); (11 pages)

Online Publication Date: June 22, 2012

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The articulation of some special pronunciations of vowel inconsistently raises with the rapid speech transmission index (RASTI) tested using mono-syllables for Chinese phonics. In the researching of speech intelligibility in room, the factors being considered have to include not only the qualities of sound field but the pronunciation characteristics of syllables as well. Therefore, with regard to the defect of RASTI measurements, we utilized the autocorrelation and the cepstrum of mono-syllables recorded in rooms to compare the articulation with the physical phenomena of intelligibilities. Thus, we found that the minimum effective duration of autocorrelation function ({lower case tau}e) of all testing syllables signals recorded at same surveyed position in rooms, associated well with the articulation for each individual room. Specially, for individual syllable signals, they are further shown significant correlation between the cepstral energy of mono-syllables and the articulation collected in all rooms. The cepstrum acts as a spatially intelligible detector for syllables, and the autocorrelation is a good response of the pronunciation characteristics of syllables.
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43.55.Hy Subjective effects in room acoustics, speech in rooms
43.71.Gv Measures of speech perception (intelligibility and quality)
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Binaural room impulse response database acquired from a variable acoustics classroom

Zhao Peng, Siu-Kit Lau, Lily M. Wang, Sean D. Browne, and Kenneth P. Roy

POMA Volume 15, pp. 015003 (February 2013); (9 pages)

Online Publication Date: February 13, 2013

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Room measurements were conducted in a variable acoustics classroom mockup space (epod) at Armstrong World Industries in Lancaster, Pennsylvania, USA. Binaural room impulse responses were measured in the epod using a head and torso simulator. Five reverberation time (RT) scenarios were achieved with various combinations of absorptive wall panels and acoustical ceiling tile. These provided a range of mid-frequency RTs from 0.4 to 1.1 seconds. Three of the five RT scenarios were achieved using two different material configurations to also consider material location effects. For each of the eight material configurations, two student-teacher orientations were tested. One orientation had all desks facing the front of the room across the long dimension of the space, while the other had all furniture facing the front of the room along the short dimension of the space. Binaural impulse responses were measured at nine student positions in the longitudinal orientation and ten student positions in the transverse orientation, both using two teacher positions. This database of 252 binaural impulse responses from a variable acoustics classroom provides realistic test cases rather than simulations. These are being used for acoustic investigations on various topics including effects of classroom furniture orientation or acoustic material arrangements.
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43.55.Dt Sound absorption in enclosures: theory and measurement; use of absorption in offices, commercial and domestic spaces
43.55.Gx Studies of existing auditoria and enclosures
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