Temporal coding and music perception in bimodal listeners

OBJECTIVE

Limited low frequency (LF) pitch and temporal fine structure (TFS) sensitivity have been thought to contribute significantly to poor music perception in cochlear implant (CI) listeners. Thus, this study aimed to evaluate music perception in relation to LF pitch perception and temporal coding, specifically in people with bimodal stimulation as a promising approach to improve spectro-temporal sensitivity in CI listeners.

METHODS

Eleven postlingually deafened bimodal listeners participated in the study (mean age=55.5 years, range 36-75 years, SD=11.7). LF pitch/TFS sensitivity was evaluated by using two recently developed tests: Harmonic Intonation (HI) and Disharmonic Intonation (DI). The music perception protocol was based on three audio files in the genres of Classical, Jazz and Soul music and a music quality questionnaire regarding four subjective aspects: Clarity, Pleasantness, Naturalness and General Quality of Sounds.

RESULTS

CI alone and bimodal findings showed statistically significant differences for both temporal coding and music perception. DI findings showed statistically significant correlations with music quality ratings (p<0.05).

CONCLUSION

Bimodal music quality ratings were significantly better, indicating a significant improvement in the quality of music towards being significantly more clear, more natural, more pleasant, and better quality. Similarly, bimodal HI/DI findings improved significantly, although the amount of benefit was greater for the DI task with spectral information only below 300 Hz. Significant DI correlations with music quality ratings supported the test to be more indicative of better temporal coding of LF residual hearing and its effects on music perception.

Binaural squelch and head shadow effects in children with unilateral cochlear implants and contralateral hearing aids

The aim of this study was to investigate the amount of binaural squelch effect (BSE) and head shadow effect (HSE) in children who use unilateral cochlear implants (CI) and contralateral hearing aids (HA). The study group consisted of 19 CI recipient children who consistently wore a contralateral HA. Speech sounds were used to evaluate speech perception performance in noise. Testing was performed in three listening conditions: (1) bimodal listening with noise source on HA side; (2) CI only with noise source contralaterally (HA off); (3) CI only with noise source on the CI side. Statistical analysis revealed a significant difference between the three listening conditions and post hoc tests indicated significant differences for all pairwise comparisons (p < 0.001). The average BSE and HSE were 11.8% and 17.1% respectively. The majority of bimodal CI users showed BSE and HSE with significant speech perception improvement in the presence of noise.