Implicit Processing of Pitch in Postlingually Deafened Cochlear Implant Users

Abstract

Cochlear implant (CI) users can only access limited pitch information through their device, which hinders music appreciation. Poor music perception may not only be due to CI technical limitations; lack of training or negative attitudes toward the electric sound might also contribute to it. Our study investigated with an implicit (indirect) investigation method whether poorly transmitted pitch information, presented as musical chords, can activate listeners’ knowledge about musical structures acquired prior to deafness. Seven postlingually deafened adult CI users participated in a musical priming paradigm investigating pitch processing without explicit judgments. Sequences made of eight sung-chords that ended on either a musically related (expected) target chord or a less-related (less-expected) target chord were presented. The use of a priming task based on linguistic features allowed CI patients to perform fast judgments on target chords in the sung music. If listeners’ musical knowledge is activated and allows for tonal expectations (as in normal-hearing listeners), faster response times were expected for related targets than less-related targets. However, if the pitch percept is too different and does not activate musical knowledge acquired prior to deafness, storing pitch information in a short-term memory buffer predicts the opposite pattern. If transmitted pitch information is too poor, no difference in response times should be observed. Results showed that CI patients were able to perform the linguistic task on the sung chords, but correct response times indicated sensory priming, with faster response times observed for the less-related targets: CI patients processed at least some of the pitch information of the musical sequences, which was stored in an auditory short-term memory and influenced chord processing. This finding suggests that the signal transmitted via electric hearing led to a pitch percept that was too different from that based on acoustic hearing, so that it did not automatically activate listeners’ previously acquired musical structure knowledge. However, the transmitted signal seems sufficiently informative to lead to sensory priming. These findings are encouraging for the development of pitch-related training programs for CI patients, despite the current technological limitations of the CI coding.

Rapid Assessment of Non-Verbal Auditory Perception in Normal-Hearing Participants and Cochlear Implant Users

“…The intensity ratings are more linked to lower activation levels of the representation of this stimulus. Thus, the results of the intensity ratings in CI users reflect a potential implicit preservation of pitch processing in the case of emotional prosody [ 32 ], as was already demonstrated in another deficit of pitch perception: congenital amusia [ 76 , 111 , 112 , 113 ]. Interestingly, the pattern of results was different for NH participants with vocoded sentences.…”

“…This could be linked to the fact that, compared to the PCD task, the participants were not asked to detect a pitch change, but rather to make a decision on a relationship between two tones, recognizing the contour. Previous work has demonstrated that CI users had remaining implicit pitch processing [ 32 ], which could have helped in this task. Moreover, in the DCI task, the pitch change sizes were bigger than in the PCD task.…”

“…Music processing and appreciation might depend on the time of deafness and implantation: post-lingually deafened and implanted patients complain more about music depreciation compared to early-deafened late-implanted patients or prelingually implanted children [ 29 ]. Furthermore, some studies suggest that CI users might have implicit processing of pitch that could help them to enjoy music [ 32 ].…”

“…Overall, studies of music perception report that music appreciation remains poor in CI users [ 8 , 16 , 23 , 24 , 25 , 26 , 27 , 28 , 29 ]. Even if it might depend on previous musical knowledge [ 31 ], music perception—especially relating to pitch [ 24 , 33 ]—could possibly still be improved with CIs despite the technical limitations thanks to implicit knowledge related to pitch [ 29 , 32 ].…”

Percepção musical e qualidade de vida em adultos usuários de implante coclear

“…Mesmo diante de toda a tecnologia aplicada aos sistemas de implantes cocleares atuais, a percepção de sons complexos, como por exemplo a música, ainda pode ser considerada por alguns usuários como uma barreira a ser transposta (Tillmann et al, 2019).…”