Sound localization models as evaluation tools for tactical communication and protective systems

Abstract

Tactical Communication and Protective Systems (TCAPS) are hearing protection devices that sufficiently protect the listener's ears from hazardous sounds and preserve speech intelligibility. However, previous studies demonstrated that TCAPS still deteriorate the listener's situational awareness, in particular, the ability to locate sound sources. On the horizontal plane, this is mainly explained by the degradation of the acoustical cues normally preventing the listener from making front-back confusions. As part of TCAPS development and assessment, a method predicting the TCAPS-induced degradation of the sound localization capability based on electroacoustic measurements would be more suitable than time-consuming behavioral experiments. In this context, the present paper investigates two methods based on Head-Related Transfer Functions (HRTFs): a template-matching model and a three-layer neural network. They are optimized to fit human sound source identification performance in open ear condition. The methods are applied to HRTFs measured with six TCAPS, providing identification probabilities. They are compared with the results of a behavioral experiment, conducted with the same protectors, and which ranks the TCAPS by type. The neural network predicts realistic performances with earplugs, but overestimates errors with earmuffs. The template-matching model predicts human performance well, except for two particular TCAPS.

Auditory model-based estimation of the effect of head-worn devices on frontal horizontal localisation

“…A neural network-based approach was proposed in [27], where the model was trained to evaluate localisation performance in the horizontal plane when HWDs were worn. The inputs in this model are: a single value to represent the ITD computed using IACC between directional impulse responses, a single value to represent the ILD computed as the difference of directional transfer function above 1.5 kHz, and a proximal stimulus that contains spectral information.…”

Measuring “Where”: A Comparative Analysis of Methods Measuring Spatial Perception

“…These studies show how individuals with hearing impairments perceive and adapt to auditory spatial information and provide valuable insights into the mechanisms and compensatory strategies they employ to navigate their acoustic environment. An additional way to explore the effect of hearing ability on sound localization is by studying typically hearing listeners who use hearing protection devices (HPDs) (e.g., [4,[10][11][12][13][14][15][16][17]). HPDs attenuate the sound's intensity, causing it to be less clear and distinctive, with a detrimental effect on the localization of the sound source [4,[7][8][9][10][11][12][13][14][15][16][17].…”

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

“…The listeners' hearing ability is another factor affecting sound localization. The contribution of hearing ability to localize sound is usually evaluated among hearing-impaired listeners e.g., [10][11][12] or among typically hearing listeners using hearing protection devices (HPDs) e.g., [4][5][6][7][8][13][14][15]. The present study was of the latter type.…”

“…HPDs affect the listener's ability to localize sound in two fundamental ways. First, they attenuate sound intensity, causing the sound to be less clear and distinctive, thus having a detrimental effect on the localization of the sound source [4][5][6][7][8][13][14][15]. This underscores the importance of considering the advantages and disadvantages of using HPDs with different attenuation levels [16].…”

“…Yet, the localization of words has rarely been studied [23][24][25], and has mainly been explored in the context of hearing aids and cochlear implants [11,12]. In contrast, pink noise e.g., [8,11,26], pure tones, and other narrow-or broad-band noise stimuli [3,4,6,8,10,15,17,25,[27][28][29][30] have been repeatedly tested in localization studies, and studies relating to military and sporting activities (such as hunting) specifically focused on the localization of gunshots [7,[31][32][33][34]. The few studies that tested the ability to localize different speech stimuli showed that speech stimuli characterized by a narrower bandwidth than pink noise or white noise were poorly localized in comparison, yet better localized than pure tones [11,[23][24][25].…”