Jeremy Marozeau

A cochlear implant user with exceptional musical hearing ability.

Abstract Although the perception of music is generally poor in cochlear implant users, there are a few excellent performers. Objective: The aim of this study was the assessment of different aspects of music perception in one exceptional cochlear implant user. Design: The assessments included pitch direction discrimination, melody and timbre recognition, relative and absolute pitch judgment, and consonance rating of musical notes presented through the sound processor(s). Study sample: An adult cochlear implant user with musical background who lost her hearing postlingually, and five normally-hearing listeners with musical training participated in the study. Results: The CI user discriminated pitch direction for sounds differing by one semitone and recognized melody with nearly 100% accuracy. Her results in timbre recognition were better than average published data for cochlear implant users. Her consonance rating, and relative and absolute pitch perception were comparable to normally-hearing listeners with musical training. Conclusion: The results in this study showed that excellent performance is possible on musical perception tasks including pitch perception using present day cochlear implant technologies. Factors that may explain this users exceptional performance are short duration of deafness, pre- and post-deafness musical training, and perfect pitch abilities before the onset of deafness.

The acoustic and perceptual cues affecting melody segregation for listeners with a cochlear implant.

Our ability to listen selectively to single sound sources in complex auditory environments is termed “auditory stream segregation.”This ability is affected by peripheral disorders such as hearing loss, as well as plasticity in central processing such as occurs with musical training. Brain plasticity induced by musical training can enhance the ability to segregate sound, leading to improvements in a variety of auditory abilities. The melody segregation ability of 12 cochlear-implant recipients was tested using a new method to determine the perceptual distance needed to segregate a simple 4-note melody from a background of interleaved random-pitch distractor notes. In experiment 1, participants rated the difficulty of segregating the melody from distracter notes. Four physical properties of the distracter notes were changed. In experiment 2, listeners were asked to rate the dissimilarity between melody patterns whose notes differed on the four physical properties simultaneously. Multidimensional scaling analysis transformed the dissimilarity ratings into perceptual distances. Regression between physical and perceptual cues then derived the minimal perceptual distance needed to segregate the melody. The most efficient streaming cue for CI users was loudness. For the normal hearing listeners without musical backgrounds, a greater difference on the perceptual dimension correlated to the temporal envelope is needed for stream segregation in CI users. No differences in streaming efficiency were found between the perceptual dimensions linked to the F0 and the spectral envelope. Combined with our previous results in normally-hearing musicians and non-musicians, the results show that differences in training as well as differences in peripheral auditory processing (hearing impairment and the use of a hearing device) influences the way that listeners use different acoustic cues for segregating interleaved musical streams.

The Sound Sensation of Apical Electric Stimulation in Cochlear Implant Recipients with Contralateral Residual Hearing

Background Studies using vocoders as acoustic simulators of cochlear implants have generally focused on simulation of speech understanding, gender recognition, or music appreciation. The aim of the present experiment was to study the auditory sensation perceived by cochlear implant (CI) recipients with steady electrical stimulation on the most-apical electrode. Methodology/Principal Findings Five unilateral CI users with contralateral residual hearing were asked to vary the parameters of an acoustic signal played to the non-implanted ear, in order to match its sensation to that of the electric stimulus. They also provided a rating of similarity between each acoustic sound they selected and the electric stimulus. On average across subjects, the sound rated as most similar was a complex signal with a concentration of energy around 523 Hz. This sound was inharmonic in 3 out of 5 subjects with a moderate, progressive increase in the spacing between the frequency components. Conclusions/Significance For these subjects, the sound sensation created by steady electric stimulation on the most-apical electrode was neither a white noise nor a pure tone, but a complex signal with a progressive increase in the spacing between the frequency components in 3 out of 5 subjects. Knowing whether the inharmonic nature of the sound was related to the fact that the non-implanted ear was impaired has to be explored in single-sided deafened patients with a contralateral CI. These results may be used in the future to better understand peripheral and central auditory processing in relation to cochlear implants.

The effect of visual cues on difficulty ratings for segregation of musical streams in listeners with impaired hearing.

Background Enjoyment of music is an important part of life that may be degraded for people with hearing impairments, especially those using cochlear implants. The ability to follow separate lines of melody is an important factor in music appreciation. This ability relies on effective auditory streaming, which is much reduced in people with hearing impairment, contributing to difficulties in music appreciation. The aim of this study was to assess whether visual cues could reduce the subjective difficulty of segregating a melody from interleaved background notes in normally hearing listeners, those using hearing aids, and those using cochlear implants. Methodology/Principal Findings Normally hearing listeners (Nu200a=u200a20), hearing aid users (Nu200a=u200a10), and cochlear implant users (Nu200a=u200a11) were asked to rate the difficulty of segregating a repeating four-note melody from random interleaved distracter notes. The pitch of the background notes was gradually increased or decreased throughout blocks, providing a range of difficulty from easy (with a large pitch separation between melody and distracter) to impossible (with the melody and distracter completely overlapping). Visual cues were provided on half the blocks, and difficulty ratings for blocks with and without visual cues were compared between groups. Visual cues reduced the subjective difficulty of extracting the melody from the distracter notes for normally hearing listeners and cochlear implant users, but not hearing aid users. Conclusion/Significance Simple visual cues may improve the ability of cochlear implant users to segregate lines of music, thus potentially increasing their enjoyment of music. More research is needed to determine what type of acoustic cues to encode visually in order to optimise the benefits they may provide.

‘Like Pots and Pans Falling Down the Stairs’. Experience of Music Composed for Listeners with Cochlear Implants in a Live Concert Setting

Abstract This study investigated whether music specially written for people with cochlear implants (CIs) could be used to better pinpoint how the music listening experience for a CI was different to a normal hearing listener (NH). After the specially arranged live concert, focus groups were formed from audience volunteers (two groups each of CIs, NHs and a range of hearing assistant devices). The theme of musical features (MF) was reported most frequently for both NHs and CIs. Valence analysis identified no significant difference in positive comments about MF by CIs than NHs for the specially commissioned works. Spatialization, although reported infrequently, was considered important by some CI, NH and bimodal listeners (who use a cochlear implant and a hearing aid). Rhythm was enjoyed by both NH and CI groups, and percussion instruments liked more than other musical instruments, but more so by CIs. Bilateral and bimodal CIs expressed interest in optimizing the hearing assistance settings, but on several occasions, the optimization ended with turning the contralateral hearing aid off. The study identifies the possible critical role of familiarity in music enjoyment.