Extended high-frequency hearing enables better talker and singer head orientation detection

Abstract

Why is the human auditory brain endowed with sensitivity to acoustical energy at frequencies beyond 8 kHz? While this “treble” range is known to be important for music quality, we hypothesize that extended high-frequency hearing capability has been obtained and retained, in part, due to its utility for the detection and perception of conspecific vocalizations (i.e., human speech and voice). More specifically, we hypothesized that access to the highest frequencies enables better detection of a vocalizer’s head orientation. To test this hypothesis, we assessed human listeners’ ability to detect changes in talker and singer head orientations, and the effect of removing access to the highest frequencies on that ability. Detection of head orientation was significantly impaired by low-pass filtering at 8 and even 10 kHz. One implication is that extended high-frequency hearing loss might impair a listener’s ability to detect whether a talker is facing the listener—a skill presumably useful for “cocktail party” listening.