Effects of Temporal and Spectral Alterations of Speech Feedback on Speech Production by Persons With Hearing Loss

Abstract

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). Methods: 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. Subjects: 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. Results: 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. Conclusions: 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 boneconducted SF (particularly in the low-frequency region) among the HA users.

Control of speech and voice in cochlear implant patients

“…14,17,[25][26][27] Other evidence for vocal pitch control in CI users is found in studies showing decreased F0 in the presence of delayed auditory feedback, a reflexive behavior seen in NH individuals. 29,30 However, in contrast to studies showing changes in voice with acute changes in hearing, other studies have found more heterogeneous results. Some adults did not reduce F0 or SPL, whereas others actually increased these parameters.…”

“…Delays in auditory feedback, known to cause slower speech and speech errors in NH listeners, also result in slower speaking rates in CI recipients. 29…”

“…Similar to loudness, some adult users exhibit elevated F0 when the implant is turned off and subsequent decrease in pitch when switched on . Other evidence for vocal pitch control in CI users is found in studies showing decreased F0 in the presence of delayed auditory feedback, a reflexive behavior seen in NH individuals . However, in contrast to studies showing changes in voice with acute changes in hearing, other studies have found more heterogeneous results.…”

“…Despite the absence of long‐term speaking rate effects, there is some evidence that auditory feedback can affect speaking rate over shorter periods. Delays in auditory feedback, known to cause slower speech and speech errors in NH listeners, also result in slower speaking rates in CI recipients …”