Pleasantness Ratings for Harmonic Intervals With Acoustic and Electric Hearing in Unilaterally Deaf Cochlear Implant Patients

Abstract

BackgroundHarmony is an important part of tonal music that conveys context, form and emotion. Two notes sounded simultaneously form a harmonic interval. In normal-hearing (NH) listeners, some harmonic intervals (e.g., minor 2nd, tritone, major 7th) typically sound more dissonant than others (e.g., octave, major 3rd, 4th). Because of the limited spectro-temporal resolution afforded by cochlear implants (CIs), music perception is generally poor. However, CI users may still be sensitive to relative dissonance across intervals. In this study, dissonance ratings for harmonic intervals were measured in 11 unilaterally deaf CI patients, in whom ratings from the CI could be compared to those from the normal ear.MethodsStimuli consisted of pairs of equal amplitude MIDI piano tones. Intervals spanned a range of two octaves relative to two root notes (F3 or C4). Dissonance was assessed in terms of subjective pleasantness ratings for intervals presented to the NH ear alone, the CI ear alone, and both ears together (NH + CI). Ratings were collected for both root notes for within- and across-octave intervals (1–12 and 13–24 semitones). Participants rated the pleasantness of each interval by clicking on a line anchored with “least pleasant” and “most pleasant.” A follow-up experiment repeated the task with a smaller stimulus set.ResultsWith NH-only listening, within-octave intervals minor 2nd, major 2nd, and major 7th were rated least pleasant; major 3rd, 5th, and octave were rated most pleasant. Across-octave counterparts were similarly rated. With CI-only listening, ratings were consistently lower and showed a reduced range. Mean ratings were highly correlated between NH-only and CI-only listening (r = 0.845, p < 0.001). Ratings were similar between NH-only and NH + CI listening, with no significant binaural enhancement/interference. The follow-up tests showed that ratings were reliable for the least and most pleasant intervals.DiscussionAlthough pleasantness ratings were less differentiated for the CI ear than the NH ear, there were similarities between the two listening modes. Given the lack of spectro-temporal detail needed for harmonicity-based distinctions, temporal envelope interactions (within and across channels) associated with a perception of roughness may contribute to dissonance perception for harmonic intervals with CI-only listening.

Effect of Sound Coding Strategies on Music Perception with a Cochlear Implant

“…Observations on CI patients with contralateral normal hearing are in line with this mechanistic explanation. CI patients appear to be sensitive to dissonance by the perception of roughness, and the information related to the temporal envelope plays an important role in distinguishing harmonicity from dissonance [ 40 ]. In our study, reducing the spectral distortions without altering the rhythmic information by CrystalisXDP sound processing strategy improved total scores, leading to the hypothesis that by providing discrete cues on roughness and beating, it could enhance global music perception.…”

“…Patients had been implanted for a mean duration of 8 ± 1.2 years [ 3 , 4 , 5 , 6 , 7 , 8 , 9 , 10 , 11 , 12 , 13 , 14 , 15 , 16 , 17 , 18 , 19 ] before inclusion. The hearing deprivation period before implantation was 9 ± 3.1 years [ 1 , 2 , 3 , 4 , 5 , 6 , 7 , 8 , 9 , 10 , 11 , 12 , 13 , 14 , 15 , 16 , 17 , 18 , 19 , 20 , 21 , 22 , 23 , 24 , 25 , 26 , 27 , 28 , 29 , 30 , 31 , 32 , 33 , 34 , 35 , 36 , 37 , 38 , 39 , 40 , …”

“…Although the perception of tempo raises no difficulty in CI, the perception of mode remains a challenging issue. In contrast to the major mode, minor music contains intervals such as minor third intervals, which induce significant roughness or dissonance in the auditory filter [ 40 ]. Accordingly, we hypothesized that, with a poor pitch resolution, CI patients would have difficulty distinguishing happy from sad music using spectral cues, but that reducing the spectral distortion would enhance this capacity.…”

The perception of emotion in music by people with hearing loss and people with cochlear implants

“…However, CI users perform markedly more poorly than people with normal hearing in judging melodic contours [87]. They are also poor at discriminating differences in musical harmony and in judging consonance or dissonance [88] (for a review, see [16]). Despite their limited ability to discriminate some features of music, many CI users report that they enjoy listening to music, and some play musical instruments.…”

Musical Interval Perception With a Cochlear Implant Alone and With a Contralateral Normal Hearing Ear

“… Landsberger et al (2020) demonstrated that SSD CI users preferred listening to music with both their NH ear and their contralateral CI despite demonstrating in the same individuals that music sounds dramatically worse when presented to only the CI ear than when presented to only the NH ear. A follow-up experiment ( Spitzer et al, 2019 ) suggests that the improvement in music perception from listening with a CI and NH ear is not because of improved perception of consonance or dissonance.…”