Situational Awareness: The Effect of Stimulus Type and Hearing Protection on Sound Localization

Abstract

The purpose of the current study was to test sound localization of a spoken word, rarely studied in the context of localization, compared to pink noise and a gunshot, while taking into account the source position and the effect of different hearing protection devices (HPDs) used by the listener. Ninety participants were divided into three groups using different HPDs. Participants were tested twice, under with- and no-HPD conditions, and were requested to localize the different stimuli that were delivered from one of eight speakers evenly distributed around them (starting from 22.5°). Localization of the word stimulus was more difficult than that of the other stimuli. HPD usage resulted in a larger mean root-mean-square error (RMSE) and increased mirror image reversal errors for all stimuli. In addition, HPD usage increased the mean RMSE and mirror image reversal errors for stimuli delivered from the front and back, more than for stimuli delivered from the left and right. HPDs affect localization, both due to attenuation and to limitation of pinnae cues when using earmuffs. Difficulty localizing the spoken word should be considered when assessing auditory functionality and should be further investigated to include HPDs with different attenuation spectra and levels, and to further types of speech stimuli.

The effects of hearing protection devices on spatial awareness in complex listening environments

“…While performance decreases under simulated NIHL conditions using low-pass filtered speech streams, the change is not significant for any measure and marginal compared to the changes observed with the OTE HPDs. This may be attributed to use of a longer speech stream compared to short noise bursts or single words [ 15 , 36 – 43 ], which allows the listener to apply a search strategy to locate the target. Head movements are known to assist the listener in resolution of ambiguities in source location [ 50 , 61 – 63 ].…”

“…Accurate sound localization contributes to situational awareness and influences rapid decision making. HPDs both reduce overall access to sound and disrupt access to auditory cues responsible for key spatial orientation tasks such as localization accuracy and front-back distinction [ 11 – 15 ]. Occupational NIHL typically reduces access to high-frequency spectral cues, which may serve to further disrupt localization abilities [ 16 – 19 ].…”

“…This includes findings that stimuli are better localized when they are broadband [ 31 , 32 ], longer in length [ 33 ], and salient [ 34 , 35 ]. While prior studies have explored the impact of HPDs and NIHL on spatial perception, an important limitation is the common use of impulse or short duration stimuli [ 15 , 36 – 43 ], which lacks ecological validity for many non-combat related emergency response situations. Public Safety operations often entail communication tasks that require the listener to monitor, process, and respond to two or more simultaneous speech streams [ 44 ].…”

The Effect of Hearing Aids on Sound Localization in Mild Unilateral Conductive Hearing Loss

“…Additional information on the software and the way by which we evaluated the localization is found in our previous publication. 23 Three different modes were tested and compared:…”

“…Additional information on the software and the way by which we evaluated the localization is found in our previous publication. 23 Three different modes were tested and compared: To assess the efficacy of ear plugging in simulating UCHL, a preliminary pure-tone audiometry with HA was conducted in 2 participants at 500-8000 Hz (Figure 2). This preliminary assessment was performed in FF, with a standard 3M disposable ear plug in the contralateral (left) ear and supra-aural headphones.…”