TWO SIMPLIFIED MODELS OF EARLY SOUND REFLECTIONS IN A ROOM
DOI:
https://doi.org/10.18372/1990-5548.65.14991Keywords:
Early sound reflections, speech intelligibility, room impulse response model, model parameters, number of reflectionsAbstract
Reverberation can be considered as a significant interference if the voice control of the unmanned aerial vehicle is performed by an indoor operator. In this paper, two simplified models of early sound reflections in a room are considered. The first model is a single reflection at a time interval of 0–50 ms. The second model is a set of reflections randomly distributed over the same time interval. For both models, speech intelligibility was calculated according to Speech Transmission Index method and Schroeder’s formula. This made it possible to obtain functional dependences of speech intelligibility on the early reflections models parameters. The obtained results for the first model are consistent with the results of earlier studies, which confirm the validity of the method used. An analysis of the statistical properties of the second model showed that an increase in the number of reflections from 2 to 8 results in a decrease, in average, of speech intelligibility from “excellent” to “good” for reverberation times 0.4–1 s. Increasing the reflections number to 18 leads to the reduced speech intelligibility close to the border between “good” and “fair”. Further increasing of the reflections number almost does not improve speech intelligibility. It was also found that there is a much larger scatter in speech intelligibility values for a small number of early reflections than for a large number of ones. Analysis of this phenomenon allows one to conclude about the danger of strong early reflections located near the end of the 0–50 ms interval.
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