Volume 121, Issue 1, January 2007
Index of content:
- ARCHITECTURAL ACOUSTICS 
121(2007); http://dx.doi.org/10.1121/1.2390665View Description Hide Description
Extensive objective energy-based parameters have been measured in 12 Mudejar-Gothic churches in the south of Spain. Measurements took place in unoccupied churches according to the ISO-3382 standard. Monoaural objective measures in the frequency range and in their spatial distributions were obtained. Acoustic parameters: clarity , definition , sound strength and center time have been deduced using impulse response analysis through a maximum length sequencemeasurement system in each church. These parameters spectrally averaged according to the most extended criteria in auditoria in order to consider acoustic quality were studied as a function of source-receiver distance. The experimental results were compared with predictions given by classical and other existing theoretical models proposed for concert halls and churches. An analytical semi-empirical model based on the measured values of the parameter is proposed in this work for these spaces. The good agreement between predicted values and experimental data for definition, sound strength, and center time in the churches analyzed shows that the model can be used for design predictions and other purposes with reasonable accuracy.
121(2007); http://dx.doi.org/10.1121/1.2382499View Description Hide Description
For ideal speech communication in public spaces, it is important to determine the optimum speech level for various background noise levels. However, speech intelligibility scores, which is conventionally used as the subjective listening test to measure the quality of speech communication, is near perfect in most everyday situations. For this reason, it is proposed to determine optimum speech levels for speech communication in public spaces by using listening difficulty ratings. Two kinds of listening test were carried out in this work. The results of the tests and our previous work [M. Morimoto, H. Sato, and M. Kobayashi, J. Acoust. Soc. Am.116, 1607–1613 (2004)] are jointly discussed for suggesting the relation between the optimum speech level and background noise level. The results demonstrate that: (1) optimum speech level is constant when background noise level is lower than , (2) optimum speech level appears to be the level, which maintains around of SN ratio when the background noise level is more than , and (3) listening difficulty increases as speech level increases under the condition where SN ratio is good enough to keep intelligibility near perfect.
121(2007); http://dx.doi.org/10.1121/1.2387134View Description Hide Description
Perceptual compensation for reverberation was measured by embedding test words in contexts that were either spoken phrases or processed versions of this speech. The processing gave steady-spectrum contexts with no changes in the shape of the short-term spectral envelope over time, but with fluctuations in the temporal envelope. Test words were from a continuum between “sir” and “stir.” When the amount of reverberation in test words was increased, to a level above the amount in the context, they sounded more like “sir.” However, when the amount of reverberation in the context was also increased, to the level present in the test word, there was perceptual compensation in some conditions so that test words sounded more like “stir” again. Experiments here found compensation with speech contexts and with some steady-spectrum contexts, indicating that fluctuations in the context’s temporal envelope can be sufficient for compensation. Other results suggest that the effectiveness of speech contexts is partly due to the narrow-band “frequency-channels” of the auditory periphery, where temporal-envelope fluctuations can be more pronounced than they are in the sound’s broadband temporal envelope. Further results indicate that for compensation to influence speech, the context needs to be in a broad range of frequency channels.
121(2007); http://dx.doi.org/10.1121/1.2395920View Description Hide Description
Sound transmission loss through double panels is studied with a patch-mobility approach. An overview of the method is given with details on acoustic and structural patch mobilities. Plate excitation is characterized by blocked patch pressures that take into account room geometry and source location. Hence, panel patch velocities before coupling can be determined and used as excitation in the mobility model. Then a convergence criterion of the model is given. Finally, transmission loss predicted with a patch-mobility method is compared with measurements.