Reaching to Sounds Improves Spatial Hearing in Bilateral Cochlear Implant Users

Abstract

Objectives: We assessed if spatial hearing training improves sound localization in bilateral cochlear implant (BCI) users and whether its benefits can generalize to untrained sound localization tasks. Design: In 20 BCI users, we assessed the effects of two training procedures (spatial versus nonspatial control training) on two different tasks performed before and after training (head-pointing to sound and audiovisual attention orienting). In the spatial training, participants identified sound position by reaching toward the sound sources with their hand. In the nonspatial training, comparable reaching movements served to identify sound amplitude modulations. A crossover randomized design allowed comparison of training procedures within the same participants. Spontaneous head movements while listening to the sounds were allowed and tracked to correlate them with localization performance. Results: During spatial training, BCI users reduced their sound localization errors in azimuth and adapted their spontaneous head movements as a function of sound eccentricity. These effects generalized to the head-pointing sound localization task, as revealed by greater reduction of sound localization error in azimuth and more accurate first head-orienting response, as compared to the control nonspatial training. BCI users benefited from auditory spatial cues for orienting visual attention, but the spatial training did not enhance this multisensory attention ability. Conclusions: Sound localization in BCI users improves with spatial reaching-to-sound training, with benefits to a nontrained sound localization task. These findings pave the way to novel rehabilitation procedures in clinical contexts.

Spontaneous head-movements improve sound localization in aging adults with hearing loss

“…Finally, although in the present study head-movements were implemented spontaneously, active head-orienting to sounds could be trained. Studies in this direction have already been conducted in normal hearing young adults with one ear plugged, to simulate a unilateral hearing loss condition (i.e., Valzolgher et al, 2020bValzolgher et al, , 2022b and in bilateral cochlear implant users (Valzolgher et al, 2022a). A relevant future direction for research would be to test training paradigms to promote effective behavioral strategies during sound localization even in ARHL.…”

“…The auditory target was a white-noise (43–22000 Hz; sample rate: 44100 Hz), with an 80% amplitude-modulation at 2.5 Hz. We adopted this broadband stimulus to preserve processing of all frequencies available to each ear (Hofman et al, 1998 ; Savel et al, 2009 ; Gaveau et al, 2022 ; Valzolgher et al, 2022a ). Moreover, we modulate noise's amplitude to facilitate ITD processing by reducing phase ambiguities (Macpherson and Middlebrooks, 2002 ).…”

Audiovisual Training in Virtual Reality Improves Auditory Spatial Adaptation in Unilateral Hearing Loss Patients

“…Anatomically, this can be explained by the presence of direct projections originating from the representation of the peripheral visual fields in the pre-striate cortex [ 20 ] towards the caudal areas of the auditory cortex, which are involved in spatial processing [ 21 ]. A large body of studies proved that multisensory stimulation that includes visual feedback is more effective than unisensory stimulation in normal-hearing participants with monaural plugs [ 15 , 16 , 18 , 22 ] and in patients with cochlear implants [ 17 , 23 ]. The study of [ 15 ] suggests that unisensory auditory training, applied to normal-hearing participants with ear plugs, showed no improvement in spatial behavior.…”

“…In the present study, we aimed to explore the behavioral mechanisms adopted by adults with UHL to compensate for their binaural deficit. Our main objective was to assess the efficacy of the spatial training program on the localization abilities of participants with unilateral moderate to profound hearing loss, as has already been performed in previous studies on normal-hearing participants with monaural plugs [ 16 ] and bilateral cochlear implants [ 17 ]. We also aimed to decipher the adaptive behavioral mechanisms used to improve spatial skills by UHL participants.…”

Capturing Visual Attention With Perturbed Auditory Spatial Cues

“…Before starting the experiment, all participants signed an informed consent document, which had received ethical approval from the national ethics committee in France (Ile de France X, N° ID RCB 2019-A02293-54) and registered as clinical trial (clinicaltrials.gov: NCT04183348). The present work focuses on the data collected in the context of a broader sound localization training protocol during the pre-training session only (full results are published in Valzolgher, Todeschini et al, 2022 ; Valzolgher, Gatel, et al, 2022 ; Valzolgher, Bouzaid, et al, 2023 ; and Alzaher et al, 2023 , for NH, bCI, uCI, and uHL participants, respectively). Although the sample size was determined by the research question of the training studies, it is noteworthy that the sample size in each of the groups matches the numerosity of a previous study that investigated a similar experimental question ( Pavani et al, 2017 , N = 17).…”