The effect of early and late reflections on binaural unmasking
* Presenting author
Abstract:
In rooms, the auditory system has to deal with incoming reflections over time, starting with a few reflections right after the direct sound and increasing in density to diffuse reverberation. The sparse early reflections are considered useful for detecting sounds in noisy backgrounds while late reflections can be detrimental. To investigate the effect of early and late reflections on binaural unmasking from a fundamental perspective, two experiments were conducted with a harmonic complex tone, centered around 500 Hz, from the front or at 60° azimuth in a simulated room with a constant anechoic noise masker at 0°. First, early reflections were progressively added to the harmonic target sound and detection thresholds were measured. While thresholds remain unchanged for a target at 60°, they significantly improve for a frontal source. In the second experiment, early reflections were progressively removed from the room impulse response so that listeners can exploit late reflections. Even if reflections are delayed and not energetically favorable, listeners’ detection thresholds improved compared to only the direct sound. While a simple model based on equalization and cancellation fails to predict the measured binaural benefit, considering dynamic processing of interaural cues improves the prediction of the measured results.