Using ISO 3382 measures, and their extensions, to evaluate acoustical conditions in concert halls

Abstract

Application of the ISO 3382 standard can lead to the acquisition of large amounts of data describing conditions in a hall. The data could include the values of a number of measures at 6 or more octave band frequencies and for many combinations of source and receiver location. This paper discusses and gives examples of using this data to find important acoustical features. The amount of data can be reduced by calculating average values over the entire data set or for each sub-area of the hall. Various important spatial variations can often be better understood from plots of values versus source-receiver distance. The analysis approach will depend on the purpose of the study, which could be for comparisons with various criteria, for investigations of problems, or to better understand the acoustical properties of the hall. The significance of new measurements can be determined by comparing values: with proposed ideal criteria, with values in well-known halls, or with theoretical predictions. The importance of differences between two values should be considered in terms of published just noticeable differences for particular measures. Separately examining early-and latearriving sound levels can be a useful diagnostic tool for better understanding the acoustical properties of halls.

Evaluation of acoustical conditions for speech communication in working elementary school classrooms

“…Here results for the mid-frequency range, obtained from the double-octave band including the 500 and 1k Hz octaves, are assumed to be important for speech. In addition to G values obtained from the complete impulse response, G 50 values for the initial 50 ms of the impulse response and G late values for the remaining part of the impulse responses were also determined (as described in [14]). …”

Measuring Room Impulse Responses: Impact of the Decay Range on Derived Room Acoustic Parameters

“…Standards for measuring these room acoustic parameters, such as ISO 3382 [1,2,3], in manycases do not, or only partially,s pecify the requirements that am easured impulse response should meet to allowc alculation of a certain parameter.For instance, to determine the reverberation time, clear requirements are stated with regard to the exponential shape of the decay curvea nd the associated decay range, i.e. the T 30 can only be calculated if the decay range is at least 45 dB while for T 20 the requirement is adecay range of at least 35 dB.…”

Calculation of impulse responses and acoustic parameters in a hall by the finite-difference time-domain method

“…In other words, the sound absorption effects of panel vibration and Helmholtz resonance in the rib wall at low frequencies were not considered in the calculation because these effects cannot be measured by the impedance-tube method. The other room acoustic parameters obtained from the impulse response-definition D 50 ; clarity C 80 ; and center time T S -(specified in ISO 3382) were calculated for the frequency range including the two octave bands of 500 Hz and 1 kHz in order to reduce the interference effects [13,14]. For both FDTD calculation and measurement, the parameters were deduced from the impulse responses for 1 second.…”