Quantification and subjective perception of varying reflection densities in measured room impulse responses

This project focuses on quantifying and testing the subjective perception of reflection densities, or the number of reflections per second, from different room impulse responses. The widely used room acoustic metric, reverberation time, is linked to the perceived reverberation in a room. Two different rooms having the same reverberation time, though, can have different reflection densities in their room impulse responses, and this difference in reflection density may affect how listeners perceive spatial impression in rooms. To investigate how sensitive humans are to a change of reflection density, this paper first reviews assorted parameters for quantifying reflection density from measured room impulse responses. A number of parameters are considered that can impact a metric for reflection density, including the resolution due to the sampling frequency, the applied time window, and the cut-off level for including a reflection in the count. A developed quantification method is subsequently applied to select a range of reflection densities from realistic room impulse responses for use in a perceptual study on determining the maximum audible reflection density by humans. Both speech and clapping signals are convolved with the assorted impulse responses for testing. Results from this study provide further insight on how humans perceive sound in rooms through linking temporal behavior of reflections with spatial perception.