Quantifying impacts of hearing protection devices on sound localization in azimuth and elevation: Refinement of acoustic predictors

Modern hearing protection devices (HPDs) mitigate the risk of noise-induced hearing loss when used as intended, but negative auditory perceptual side-effects continue to limit usability in critical settings. Dozens of studies have shown that HPDs lead to significant errors in sound source localization. Several studies, including previous studies by our group, have linked such errors to distortions of the spectra of transmitted signals. Here we provide an update on a multi-site effort to develop acoustic predictors and summary metrics to quantify HPD impacts on sound source localization. At two independent study sites, human listeners localized brief broadband signals with open ears and during use of passive and active earplug and earmuff-style devices. Sources spanning 360° in azimuth and −30° to + 60° in elevation enabled measurement of two-dimensional localization error across a broad range of source locations. An initial set of parallel acoustic measurements was obtained using a standardized acoustic test fixture. Present efforts are focused on evaluating prospective advantages of (1) incorporating binaural acoustic data in the prediction of errors and (2) accounting for individual HPD-impacted acoustic variability. The long-term goal of this work is to support application-specific selection of existing HPDs and inform the design of new HPDs.