Comparing Sound Localization Deficits in Bilateral Cochlear-Implant Users and Vocoder Simulations With Normal-Hearing Listeners

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.

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Combined Effects of Noise and Reverberation on Sound Localization for Listeners With Normal Hearing and Bilateral Cochlear Implants

American Journal of Audiology ◽

10.1044/2017_aja-16-0101 ◽

2017 ◽

Vol 26 (4) ◽

pp. 519-530

Author(s):

Yunfang Zheng ◽

Janet Koehnke ◽

Joan Besing

Keyword(s):

Cochlear Implant ◽

Cochlear Implants ◽

Sound Localization ◽

Noise Source ◽

Normal Hearing ◽

Combined Effects ◽

Bilateral Cochlear Implants ◽

Processing Strategies ◽

Localization Test ◽

The Individual

Purpose This study examined the individual and combined effects of noise and reverberation on the ability of listeners with normal hearing (NH) and with bilateral cochlear implants (BCIs) to localize speech. Method Six adults with BCIs and 10 with NH participated. All subjects completed a virtual localization test in quiet and at 0-, −4-, and −8-dB signal-to-noise ratios (SNRs) in simulated anechoic and reverberant (0.2-, 0.6-, and 0.9-s RT 60 ) environments. BCI users were also tested at +8- and +4-dB SNR. A 3-word phrase was presented at 70 dB SPL from 9 simulated locations in the frontal horizontal plane (±90°), with the noise source at 0°. Results BCIs users had significantly poorer localization than listeners with NH in all conditions. BCI users' performance started to decrease at a higher SNR (+4 dB) and shorter RT 60 (0.2 s) than listeners with NH (−4 dB and 0.6 s). The combination of noise and reverberation began to degrade localization of BCI users at a higher SNR and a shorter RT 60 than listeners with NH. Conclusion The clear effect of noise and reverberation on the performance of BCI users provides information that should be useful for refining cochlear implant processing strategies and developing cochlear implant rehabilitation plans to optimize binaural benefit for BCI users in everyday listening situations.

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Sound Localization in Noise by Normal-Hearing Listeners and Cochlear Implant Users

Ear and Hearing ◽

10.1097/aud.0b013e318257607b ◽

2012 ◽

Vol 33 (4) ◽

pp. 445-457 ◽

Cited By ~ 61

Author(s):

Stefan Kerber ◽

Bernhard U. Seeber

Keyword(s):

Cochlear Implant ◽

Sound Localization ◽

Normal Hearing

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Sound localization, speech and tone recognition for stimuli presented from the rear in bilateral cochlear implant users

International Journal of Audiology ◽

10.1080/14992027.2020.1866218 ◽

2021 ◽

pp. 1-10

Author(s):

Yu Zheng ◽

Ning Cong ◽

Na Gao ◽

Fanglu Chi ◽

Yibo Huang ◽

...

Keyword(s):

Cochlear Implant ◽

Sound Localization ◽

Bilateral Cochlear Implant ◽

Tone Recognition

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Reweighting of Binaural Localization Cues in Bilateral Cochlear-Implant Listeners

Journal of the Association for Research in Otolaryngology ◽

10.1007/s10162-021-00821-3 ◽

2021 ◽

Author(s):

Maike Klingel ◽

Bernhard Laback

Keyword(s):

Cochlear Implant ◽

Sound Localization ◽

Visual Information ◽

Electrode Pair ◽

Optimal Conditions ◽

Visual Reinforcement ◽

Pulse Trains ◽

Before And After ◽

Bilateral Cochlear Implant ◽

Binaural Localization

AbstractNormal-hearing (NH) listeners rely on two binaural cues, the interaural time (ITD) and level difference (ILD), for azimuthal sound localization. Cochlear-implant (CI) listeners, however, rely almost entirely on ILDs. One reason is that present-day clinical CI stimulation strategies do not convey salient ITD cues. But even when presenting ITDs under optimal conditions using a research interface, ITD sensitivity is lower in CI compared to NH listeners. Since it has recently been shown that NH listeners change their ITD/ILD weighting when only one of the cues is consistent with visual information, such reweighting might add to CI listeners’ low perceptual contribution of ITDs, given their daily exposure to reliable ILDs but unreliable ITDs. Six bilateral CI listeners completed a multi-day lateralization training visually reinforcing ITDs, flanked by a pre- and post-measurement of ITD/ILD weights without visual reinforcement. Using direct electric stimulation, we presented 100- and 300-pps pulse trains at a single interaurally place-matched electrode pair, conveying ITDs and ILDs in various spatially consistent and inconsistent combinations. The listeners’ task was to lateralize the stimuli in a virtual environment. Additionally, ITD and ILD thresholds were measured before and after training. For 100-pps stimuli, the lateralization training increased the contribution of ITDs slightly, but significantly. Thresholds were neither affected by the training nor correlated with weights. For 300-pps stimuli, ITD weights were lower and ITD thresholds larger, but there was no effect of training. On average across test sessions, adding azimuth-dependent ITDs to stimuli containing ILDs increased the extent of lateralization for both 100- and 300-pps stimuli. The results suggest that low-rate ITD cues, robustly encoded with future CI systems, may be better exploitable for sound localization after increasing their perceptual weight via training.

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The Effect of Microphone Placement on Interaural Level Differences and Sound Localization Across the Horizontal Plane in Bilateral Cochlear Implant Users

Ear and Hearing ◽

10.1097/aud.0000000000000297 ◽

2016 ◽

Vol 37 (5) ◽

pp. e341-e345 ◽

Cited By ~ 7

Author(s):

Heath G. Jones ◽

Alan Kan ◽

Ruth Y. Litovsky

Keyword(s):

Cochlear Implant ◽

Sound Localization ◽

Horizontal Plane ◽

Bilateral Cochlear Implant ◽

Interaural Level Differences

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Effect of Synchronized Linked Band Selection on Speech Intelligibility of Bilateral Cochlear Implant Users

10.31234/osf.io/8zycu ◽

2020 ◽

Author(s):

Tom Gajęcki ◽

Waldo Nogueira

Keyword(s):

Electrical Stimulation ◽

Cochlear Implant ◽

Background Noise ◽

Speech Intelligibility ◽

Signal To Noise Ratio ◽

Normal Hearing ◽

Band Selection ◽

Signal To Noise ◽

Intelligibility Test ◽

Bilateral Cochlear Implant

Normal hearing listeners have the ability to exploit the audio input perceived by each ear to extract target information in challenging listening scenarios. Bilateral cochlear implant (BiCI) users, however, do not benefit as much as normal hearing listeners do from a bilateral input. In this study, we investigate the effect that bilaterally linked band selection, bilaterally synchronized electrical stimulation and ideal binary masks (IdBMs) have on the ability of 10 BiCIs to understand speech in background noise. The performance was assessed through a sentence-based speech intelligibility test, in a scenario where the speech signal was presented from the front and the interfering noise from one side. The linked band selection relies on the most favorable signal-to-noise-ratio (SNR) ear, which will select the bands to be stimulated for both CIs. Results show that no benefit from adding a second CI to the most favorable SNR side was achieved for any of the tested bilateral conditions. However, when using both devices, speech perception results show that performing linked band selection, besides delivering bilaterally synchronized electrical stimulation, leads to an improvement compared to standard clinical setups. Moreover, the outcomes of this work show that by applying IdBMs, subjects achieve speech intelligibility scores similar to the ones without background noise.

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