Localization of novel reduced-annoyance audio interface sounds

Foley et al. [JASA 151, 3189–3196 (2022)] have demonstrated that annoyance of auditory interface sounds can be reduced both by shortening the duration of upper harmonics and by applying percussive rather than flat amplitude envelopes. However, sounds in that study had a maximum frequency of 2400 Hz, which would likely affect localization based on spectral cues. In a setting with multiple interface devices (e.g., a multi-patient hospital ward), localization of interface sounds is a concern. We characterized normally hearing listeners' ability to localize a variety of candidate reduced-annoyance interface sounds (flat or percussive envelopes; durations between 360 and 1600 ms; all but one with uppermost harmonic limited to 2400 Hz) in quiet or at + 4-dB and −11-dB SNR in spatially diffuse multi-talker babble. Listeners stood at the center of a 360-degree loudspeaker array in a darkened anechoic chamber and used a head-pointing response to report the perceived location of each target. Decreasing SNR increased response variability and the rate of front/rear confusions. For all sounds with restricted bandwidth, front/rear confusions were frequent in the absence of head movements, but when head movements were initiated before target offset, confusions were substantially reduced. The results highlight the need to consider localizability when designing improved auditory interface sounds.