Calculating Reverberation Time from Impulse Responses: A Comparison of Software Implementations

Abstract

In room acoustics measurement, calculating reverberation time from room impulse responses is often done, aided by software. This paper compares the performance of nine software implementations for calculating octave band reverberation time, including two written by the authors. Synthetic impulse responses are used to test decays without and with a steady noise floor, and an impulse response from a real measurement is also used for comparison. Results indicate no significant reverberation time calculation problems for noise-free exponential decays, and for exponential decays leading to a steady noise floor. Frequency selectivity is identified as an area for potential improvement in filter-bank design, and a highly selective octave band filter-bank is shown to be effective without introducing errors. Testing with a real measured impulse response, which had been used in a 2004 study comparing reverberation time analysis implementations, showed greater agreement between software than was found previously. This might reflect an improvement in software performance in the years between the two studies. However, it also might reflect the smaller scale of the present study. Nevertheless, the results can contribute to confidence in current software implementations.