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

Abstract

To compare the sound-source localization, discrimination, and tracking performance of bilateral cochlear implant users with omnidirectional (OMNI) and pinna-imitating (PI) microphone directionality modes. Design: Twelve experienced bilateral cochlear implant users participated in the study. Their audio processors were fitted with two different programs featuring either the OMNI or PI mode. Each subject performed static and dynamic sound field spatial hearing tests in the horizontal plane. The static tests consisted of an absolute sound localization test and a minimum audible angle test, which was measured at eight azimuth directions. Dynamic sound tracking ability was evaluated by the subject correctly indicating the direction of a moving stimulus along two circular paths around the subject. Results: PI mode led to statistically significant sound localization and discrimination improvements. For static sound localization, the greatest benefit was a reduction in the number of front-back confusions. The front-back confusion rate was reduced from 47% with OMNI mode to 35% with PI mode (p = 0.03). The ability to discriminate sound sources straight to the sides (90° and 270° angle) was only possible with PI mode. The averaged minimum audible angle value for the 90° and 270° angle positions decreased from a 75.5° to a 37.7° angle when PI mode was used (p < 0.001). Furthermore, a non-significant trend towards an improvement in the ability to track moving sound sources was observed for both trajectories tested (p = 0.34 and p = 0.27). Conclusions: Our results demonstrate that PI mode can lead to improved spatial hearing performance in bilateral cochlear implant users, mainly as a consequence of improved front-back discrimination with PI mode.

Spatial Hearing Difficulties in Reaching Space in Bilateral Cochlear Implant Children Improve With Head Movements

“…In addition, head rotations and head translations ( Wallach 1940 ; Perrett & Noble 1997 ) lead to changes in binaural cues which prove useful for resolving front–back confusion in people with NH ( Brimijoin et al 2010 ) and even more so in people with hearing impairment ( Brimijoin et al 2012 ). The impact of spontaneous head movements on auditory spatial performance has been highlighted in CI adults ( Mueller et al 2014 ; Pastore et al 2018 ; Fischer et al 2020 ), but it remains entirely overlooked in pediatric populations. This implies that current data measured in laboratory may be a limited approximation of the actual sound localization ability of children in their daily life, where head movements during sounds occur spontaneously.…”

Multichannel acoustic source and image dataset for the cocktail party effect in hearing aid and implant users

“…Originally this CI audio processor incorporates 2 of the 4 microphones which we placed at the processor (channel IDs 2, 3 (left side) or 6, 7 (right side) as described in Table 2). In addition to the 10 microphones placed on the CI audio processors, two microphones were placed at the entry of each ear canal to capture the frequency transformations of the incoming sound waves caused by the pinna 29,[48][49][50][51] . The remaining 4 microphones were attached to an elastic headband as used in Gawliczek et al 52 .…”

Electro-Haptic Stimulation: A New Approach for Improving Cochlear-Implant Listening

“…These intensity differences can be heavily distorted by independent pre-processing between devices (particularly automatic gain control; Potts et al, 2019 ). Additional factors that limit spatial hearing abilities in bilateral CI users are mismatches across devices in the perceived intensity and the place of electrical stimulation within the cochlea ( Kan et al, 2019 ) as well as the impaired perception of spectral (e.g., pinna) cues ( Fischer et al, 2020 ).…”