Auditory motion tracking ability of adults with normal hearing and with bilateral cochlear implants

Abstract

Adults with bilateral cochlear implants (BiCIs) receive benefits in localizing stationary sounds when listening with two implants compared with one; however, sound localization ability is significantly poorer when compared to normal hearing (NH) listeners. Little is known about localizing sound sources in motion, which occurs in typical everyday listening situations. The authors considered the possibility that sound motion may improve sound localization in BiCI users by providing multiple places of information. Alternatively, the ability to compare multiple spatial locations may be compromised in BiCI users due to degradation of binaural cues, and thus result in poorer performance relative to NH adults. In this study, the authors assessed listeners' abilities to distinguish between sounds that appear to be moving vs stationary, and track the angular range and direction of moving sounds. Stimuli were bandpass-filtered (150-6000 Hz) noise bursts of different durations, panned over an array of loudspeakers. Overall, the results showed that BiCI users were poorer than NH adults in (i) distinguishing between a moving vs stationary sound, (ii) correctly identifying the direction of movement, and (iii) tracking the range of movement. These findings suggest that conventional cochlear implant processors are not able to fully provide the cues necessary for perceiving auditory motion correctly. V

Pinna-Imitating Microphone Directionality Improves Sound Localization and Discrimination in Bilateral Cochlear Implant Users

“…Our findings suggest, in accordance with Moua et al (2019), that current CI processors might degrade binaural cues such as temporal fine structure. In addition, CI processors are not synchronized, and thus, different peaks might be picked up by the audio processors, leading to a nonsmooth or erroneous representation of the auditory motion image (Kan et al 2018).…”

“…Since we report results on the continuous tracking ability of BiCI users with regard to a moving stimulus for the first time, a comparison with the literature was only possible to a limited extent. Studies with moving sounds and BiCI users have been performed by Moua et al (2019) at the frontal azimuth. However, feedback was always provided after the moving stimulus was presented via nonindividualized binaural recordings.…”

“…This finding is consistent with experiments that showed reduced numbers of FBCs in hearing aid users when applying pinna-imitating microphone directionality (Keidser et al 2006;Van den Bogaert et al 2011;Mueller et al 2012;Kuk et al 2013;Jensen et al 2013).Another important aspect of spatial hearing performance is the ability to track moving sound sources, especially when realistic test conditions are desired. The ability of BiCI users to perceive and track a virtual moving stimulus in the frontal azimuth has been investigated by Moua et al (2019). They reported poor performance in discriminating the movement direction and observed overshooting when judging the actual range of sound movements.…”

Dynamic sound field audiometry: Static and dynamic spatial hearing tests in the full horizontal plane

“…Subjects in Moua et al (2019) were able to identify the direction of the sound source with an accuracy of >80%. The longer the angular distance of the trajectory was, the better the results.…”

“…The absolute sound localization tests performed with these setups are in stark contrast to reality, where we are constantly surrounded by dynamic auditory environments with moving sound sources and events. More sophisticated tests involving the perception of auditory movement require a real or simulated displacement of at least one sound source (Grantham 1997;Brimijoin & Akeroyd 2014;Moua et al 2019). While simulated moving loudspeakers avoid artificial movement noise, which can provide unwanted cues, it remains unclear to what extent they can reproduce physically moving sound sources under consideration of the requirements for clinical testing.…”