Directional loudness perception: the effect of sound incidence angle on loudness and the underlying binaural summation

Loudness, the perceived intensity of sound, is a fundamental attribute in psychoacoustics. An immense body of literature on loudness has been accumulated, and based on the reported findings, models for predicting loudness from monophonic, acoustical measurements of sound pressure have been developed. The research and modeling of loudness have mainly been concerned with the temporal and spectral aspects of sounds, while the spatial aspects have mostly been overlooked.

This PhD thesis investigates the spatial aspects of loudness perception, namely, how does the direction from which a sound reaches the listener affect its perceived loudness. The results obtained in a series of listening experiments show that loudness depends considerably on direction for a variety of sound stimuli. Furthermore,
these directional dependencies could be largely accounted for by determining binaural at-ear exposures, individually for each listener. The results of the thesis were used for developing a binaural loudness model. This model is applicable to acoustical measurements made with artificial heads, commonly used in a variety of applications, ranging from the assessment of noise annoyance to evaluating product sound
quality and the fidelity of multichannel sound reproduction systems.