Loudness and distance estimates for noise bursts coming from several distances with and without visual cues to their source

Abstract : The at-ear sound pressure decreases with the distance to the source. Since pressure plays an essential part in loudness judgments, loudness could be expected to decrease similarly with the distance to the source. Yet, several studies reported conflicting results when assessing loudness as a function of sound source distance. The present study gathers loudness judgments for noise bursts displayed from several distances from listeners in a virtual environment. A visual representation of the distant sound sources could or could not be available to the listeners in order to modify the perceived distance of these sounds since visual distance cues affect auditory distance perception. Sounds were displayed in free or diffuse fields in order to also provide auditory distance cues. The results of this study show that visual cues had no significant effect on loudness estimates, even though they significantly affected apparent source distance judgments. The discrepancy between these results and the generally accepted loudness constancy phenomenon could come from the instructions that were given to the listeners, which focused on "at-ear" loudness judgments whereas loudness constancy is predominantly obtained when asking the listeners to make loudness judgments based on the sound source power.