Acoustics of Emotional Prosody Produced by Prelingually Deaf Children With Cochlear Implants

Abstract

Purpose: Cochlear implants (CIs) provide reasonable levels of speech recognition quietly, but voice pitch perception is severely impaired in CI users. The central question addressed here relates to how access to acoustic input pre-implantation influences vocal emotion production by individuals with CIs. The objective of this study was to compare acoustic characteristics of vocal emotions produced by prelingually deaf school-aged children with cochlear implants (CCIs) who were implanted at the age of 2 and had no usable hearing before implantation with those produced by children with normal hearing (CNH), adults with normal hearing (ANH), and postlingually deaf adults with cochlear implants (ACI) who developed with good access to acoustic information prior to losing their hearing and receiving a CI. Method: A set of 20 sentences without lexically based emotional information was recorded by 13 CCI, 9 CNH, 9 ANH, and 10 ACI, each with a happy emotion and a sad emotion, without training or guidance. The sentences were analyzed for primary acoustic characteristics of the productions. Results: Significant effects of Emotion were observed in all acoustic features analyzed (mean voice pitch, standard deviation of voice pitch, intensity, duration, and spectral centroid). ACI and ANH did not differ in any of the analyses. Of the four groups, CCI produced the smallest acoustic contrasts between the emotions in voice pitch and emotions in its standard deviation. Effects of developmental age (highly correlated with the duration of device experience) and age at implantation (moderately correlated with duration of device experience) were observed, and interactions with the children's sex were also observed. Conclusion: Although prelingually deaf CCI and postlingually deaf ACI are listening to similar degraded speech and show similar deficits in vocal emotion perception, these groups are distinct in their productions of contrastive vocal emotions. The results underscore the importance of access to acoustic hearing in early childhood for the production of speech prosody and also suggest the need for a greater role of speech therapy in this area.

Keywords: acoustics; children; cochlear implants; emotion; production; speech; vocal.