Abstract
Spatial hearing is crucial in real life but deteriorates in participants with severe sensorineural hearing loss or single-sided deafness. This ability can potentially be improved with a unilateral cochlear implant (CI). The present study investigated measures of sound localization in participants with single-sided deafness provided with a CI. Sound localization was measured separately at eight loudspeaker positions (4°, 30°, 60°, and 90°) on the CI side and on the normal-hearing side. Low- and high-frequency noise bursts were used in the tests to investigate possible differences in the processing of interaural time and level differences. Data were compared to normal-hearing adults aged between 20 and 83. In addition, the benefit of the CI in speech understanding in noise was compared to the localization ability. Fifteen out of 18 participants were able to localize signals on the CI side and on the normal-hearing side, although performance was highly variable across participants. Three participants always pointed to the normal-hearing side, irrespective of the location of the signal. The comparison with control data showed that participants had particular difficulties localizing sounds at frontal locations and on the CI side. In contrast to most previous results, participants were able to localize low-frequency signals, although they localized high-frequency signals more accurately. Speech understanding in noise was better with the CI compared to testing without CI, but only at a position where the CI also improved sound localization. Our data suggest that a CI can, to a large extent, restore localization in participants with single-sided deafness. Difficulties may remain at frontal locations and on the CI side. However, speech understanding in noise improves when wearing the CI. The treatment with a CI in these participants might provide real-world benefits, such as improved orientation in traffic and speech understanding in difficult listening situations.
Highlights
Orientation in the environment is a crucial ability in everyday situations, for instance in road traffic and communication in noisy surroundings
Many of the participants tended to point to the normal-hearing side rather than the cochlear implant (CI) side
Results from these good performers showed that wearing a CI can restore localization for signals coming from the CI side and slightly enhance localization of signals on the normal hearing (NH) side
Summary
Orientation in the environment is a crucial ability in everyday situations, for instance in road traffic and communication in noisy surroundings. Acoustic information from both ears is necessary for locating a sound and understanding speech-innoise accurately. Cochlear implants (CIs) have been found to be useful to rehabilitate binaural hearing (van Hoesel and Tyler, 2003; Ching et al, 2004; Seeber et al, 2004; Dunn et al, 2008; Grossmann et al, 2016; Dillon et al, 2017a,b) and enable sound localization in SSD participants (Firszt et al, 2012; Gartrell et al, 2014; Távora-Vieira et al, 2015; Grossmann et al, 2016; Litovsky et al, 2019; Wedekind et al, 2020)
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