Effects of temporal and spectral alterations of speech feedback on speech production by persons with hearing loss.
To evaluate the effects of delay and spectral alteration of speech feedback (SF) on the speaking rate and voice pitch in adult users of hearing aids (HAs) and cochlear implants (CIs). Repeated-measure, completely crossed, 2-factor design. Spectral alterations were implemented by replacing SF with noise that was filtered into 1-, 2-, or 4-frequency bands and speech-modulated in real time. Delays varied from 25 to 200 milliseconds. Seven HA users with severe to profound hearing loss and 6 CI users were randomly recruited by public advertising. All were postlingually deafened adults with intelligible speech. The average speaking rate significantly decreased and rate variability significantly increased with increase in SF delay for both groups. Spectral alterations of SF reduced the effect on speaking rate in the HA group but not in the CI group. Spectral alterations did not significantly affect rate variability in the HA group but did so in the CI group. Average voice pitch increased significantly with increase in SF delay and with spectral alterations of SF in the HA group. No significant effects on average pitch of CI users were noted. The 2 groups were affected differently by the delay and spectral alterations of SF. The differences possibly reflect greater spectral resolution ability in the case of CI users and greater audibility of bone-conducted SF (particularly in the low-frequency region) among the HA users.