• Volume/Page
  • Keyword
  • DOI
  • Citation
  • Advanced
   
 
 
 

Journal of the Acoustical Society of America

BROWSE VOLUMES

Year Range: 
Search Issue | RSS Feeds RSS
Previous Issue Next Issue

Sep 2009

Volume 126, Issue 3, pp. EL69-1649

Return to All Sections
back to top
RSS Feeds

Identifying acoustical coupling by measurements and prediction-models for St. Peter’s Basilica in Rome

Francesco Martellotta

J. Acoust. Soc. Am. Volume 126, Issue 3, pp. 1175-1186 (2009); (12 pages) | Cited 7 times

Full Text: Read Online (HTML) | Download PDF

Show Abstract
St. Peter’s Basilica is one of the largest buildings in the world, having a huge volume resulting from the addition of different parts. Consequently, sound propagation cannot be interpreted using a conventional approach and requires experimental measures to be compared with statistical-acoustics and geometrical predictions in order to explain the interplay between shape, materials, and sound waves better. In previous research one of the most evident effects, the surprisingly low reverberation time, was believed to result from acoustical coupling phenomena. Taking advantage of more refined measuring techniques available today an acoustic survey was carried out and the results were analyzed using different methods, including Bayesian parameter estimation of multiple slope decays and directional energy plots, which showed that coupling effects actually take place, even though measured reverberation times were longer than those given in previous studies. In addition, experimental results were compared with geometrical- and statistical-acoustic models of the basilica, which showed that careful selection of input data and, in statistical models, the inclusion of phenomena such as direct sound radiation and non-diffuse energy transfer, allow obtaining accurate results. Finally, both models demonstrated that reduced reverberation depends more on increased absorption of decorated surfaces than on coupling effects.
Show PACS
43.55.Br Room acoustics: theory and experiment; reverberation, normal modes, diffusion, transient and steady-state response
43.55.Gx Studies of existing auditoria and enclosures

Investigation of acoustically coupled enclosures using a diffusion-equation model

Ning Xiang, Yun Jing, and Alexander C. Bockman

J. Acoust. Soc. Am. Volume 126, Issue 3, pp. 1187-1198 (2009); (12 pages) | Cited 10 times

Full Text: Read Online (HTML) | Download PDF

Show Abstract
Recent application of coupled-room systems in performing arts spaces has prompted active research on sound fields in these complex geometries. This paper applies a diffusion-equation model to the study of acoustics in coupled-rooms. Acoustical measurements are conducted on a scale-model of two coupled-rooms. Using the diffusion model and the experimental results the current work conducts in-depth investigations on sound pressure level distributions, providing further evidence supporting the valid application of the diffusion-equation model. Analysis of the results within the Bayesian framework allows for quantification of the double-slope characteristics of sound-energy decays obtained from the diffusion-equation numerical modeling and the experimental measurements. In particular, Bayesian decay analysis confirms sound-energy flux modeling predictions that time-dependent sound-energy flows in coupled-room systems experience feedback in the form of energy flow-direction change across the aperture connecting the two rooms in cases where the dependent room is more reverberant than the source room.
Show PACS
43.55.Br Room acoustics: theory and experiment; reverberation, normal modes, diffusion, transient and steady-state response
43.55.Ka Computer simulation of acoustics in enclosures, modeling

The variance of the discrete frequency transmission function of a reverberant room

John L. Davy

J. Acoust. Soc. Am. Volume 126, Issue 3, pp. 1199-1206 (2009); (8 pages) | Cited 3 times

Full Text: Read Online (HTML) | Download PDF

Show Abstract
This paper first shows experimentally that the distribution of modal spacings in a reverberation room is well modeled by the Rayleigh or Wigner distribution. Since the Rayleigh or Wigner distribution is a good approximation to the Gaussian orthogonal ensemble (GOE) distribution, this paper confirms the current wisdom that the GOE distribution is a good model for the distribution of modal spacings. Next this paper gives the technical arguments that the author used successfully to support the pragmatic arguments of Baade and the Air-conditioning and Refrigeration Institute of USA for retention of the pure tone qualification procedure and to modify a constant in the International Standard ISO 3741:1999(E) for measurement of sound power in a reverberation room.
Show PACS
43.55.Cs Stationary response of rooms to noise; spatial statistics of room response; random testing
43.55.Br Room acoustics: theory and experiment; reverberation, normal modes, diffusion, transient and steady-state response
43.55.Nd Reverberation room design: theory, applications to measurements of sound absorption, transmission loss, sound power
43.50.Cb Noise spectra, determination of sound power

Acoustic simulations of Mudejar-Gothic churches

Miguel Galindo, Teófilo Zamarreño, and Sara Girón

J. Acoust. Soc. Am. Volume 126, Issue 3, pp. 1207-1218 (2009); (12 pages) | Cited 2 times

Full Text: Read Online (HTML) | Download PDF

Show Abstract
In this paper, an iterative process is used in order to estimate the values of absorption coefficients of those materials of which little is known in the literature, so that an acoustic simulation can be carried out in Mudejar-Gothic churches. The estimation of the scattering coefficients, which is even less developed, is based on the size of the irregularities. This methodology implemented is applied to six Mudejar-Gothic churches of Seville (southern Spain). The simulated monophonic acoustic parameters, both in the frequency domain and as a function of source-receiver distance (spatial distribution), are analyzed and compared with the in situ measures. Good agreement has been found between these sets of values, whereby each parameter is discussed in terms of the just noticeable difference. This procedure for existing buildings, especially for those which are rich in heritage, enables a reliable evaluation of the effect on the maintenance, restoration, and conditioning for new uses, as well as the recreation of the acoustic environment of ancient times. Along these lines, the acoustic influence of the timber roof and the presence of the public in these churches have also been studied.
Show PACS
43.55.Gx Studies of existing auditoria and enclosures
43.55.Ka Computer simulation of acoustics in enclosures, modeling

Evaluating signal-to-noise ratios, loudness, and related measures as indicators of airborne sound insulation

H. K. Park and J. S. Bradley

J. Acoust. Soc. Am. Volume 126, Issue 3, pp. 1219-1230 (2009); (12 pages)

Full Text: Read Online (HTML) | Download PDF

Show Abstract
Subjective ratings of the audibility, annoyance, and loudness of music and speech sounds transmitted through 20 different simulated walls were used to identify better single number ratings of airborne sound insulation. The first part of this research considered standard measures such as the sound transmission class the weighted sound reduction index (Rw) and variations of these measures [ H. K. Park and J. S. Bradley, J. Acoust. Soc. Am. 126, 208-219 (2009) ]. This paper considers a number of other measures including signal-to-noise ratios related to the intelligibility of speech and measures related to the loudness of sounds. An exploration of the importance of the included frequencies showed that the optimum ranges of included frequencies were different for speech and music sounds. Measures related to speech intelligibility were useful indicators of responses to speech sounds but were not as successful for music sounds. A-weighted level differences, signal-to-noise ratios and an A-weighted sound transmission loss measure were good predictors of responses when the included frequencies were optimized for each type of sound. The addition of new spectrum adaptation terms to Rw values were found to be the most practical approach for achieving more accurate predictions of subjective ratings of transmitted speech and music sounds.
Show PACS
43.55.Hy Subjective effects in room acoustics, speech in rooms
Return to All Sections
Close

Home Publications Meetings Contact ASA Site Map Back to Top

Copyright © Acoustical Society of America

close