The perception of emotion and focus prosody with varying acoustic cues in cochlear implant simulations with varying filter slopes

Prosodic Focus Interpretation in Spectrotemporally Degraded Speech by Non-Native Listeners

PURPOSE

This study assesses how spectrotemporal degradations that can occur in the sound transmission of a cochlear implant (CI) may influence the ability of non-native listeners to recognize the intended meaning of utterances based on the position of the prosodically focused word. Previous research suggests that perceptual accuracy and listening effort are negatively affected by CI processing (or CI simulations) or when the speech is presented in a non-native language, in a number of tasks and circumstances. How these two factors interact to affect prosodic focus interpretation, however, remains unclear.

METHOD

In an online experiment, normal-hearing (NH) adolescent and adult native Dutch learners of English and a small control group of NH native English adolescents listened to CI-simulated (eight-channel noise-band vocoded) and non-CI-simulated English sentences differing in prosodically marked focus. For assessing perceptual accuracy, listeners had to indicate which of four possible context questions the speaker answered. For assessing listening effort, a dual-task paradigm was used with a secondary free recall task.

RESULTS

The results indicated that prosodic focus interpretation was significantly less accurate in the CI-simulated condition compared with the non-CI-simulated condition but that listening effort was not increased. Moreover, there was no interaction between the influence of the degraded CI-simulated speech signal and listening groups in either their perceptual accuracy or listening effort.

CONCLUSION

Non-native listeners are not more strongly affected by spectrotemporal degradations than native listeners, and less proficient non-native listeners are not more strongly affected by these degradations than more proficient non-native listeners.

Meta-Analysis on the Identification of Linguistic and Emotional Prosody in Cochlear Implant Users and Vocoder Simulations

OBJECTIVES

This study quantitatively assesses how cochlear implants (CIs) and vocoder simulations of CIs influence the identification of linguistic and emotional prosody in nontonal languages. By means of meta-analysis, it was explored how accurately CI users and normal-hearing (NH) listeners of vocoder simulations (henceforth: simulation listeners) identify prosody compared with NH listeners of unprocessed speech (henceforth: NH listeners), whether this effect of electric hearing differs between CI users and simulation listeners, and whether the effect of electric hearing is influenced by the type of prosody that listeners identify or by the availability of specific cues in the speech signal.

DESIGN

Records were found by searching the PubMed Central, Web of Science, Scopus, Science Direct, and PsycINFO databases (January 2018) using the search terms "cochlear implant prosody" and "vocoder prosody." Records (published in English) were included that reported results of experimental studies comparing CI users' and/or simulation listeners' identification of linguistic and/or emotional prosody in nontonal languages to that of NH listeners (all ages included). Studies that met the inclusion criteria were subjected to a multilevel random-effects meta-analysis.

RESULTS

Sixty-four studies reported in 28 records were included in the meta-analysis. The analysis indicated that CI users and simulation listeners were less accurate in correctly identifying linguistic and emotional prosody compared with NH listeners, that the identification of emotional prosody was more strongly compromised by the electric hearing speech signal than linguistic prosody was, and that the low quality of transmission of fundamental frequency (f0) through the electric hearing speech signal was the main cause of compromised prosody identification in CI users and simulation listeners. Moreover, results indicated that the accuracy with which CI users and simulation listeners identified linguistic and emotional prosody was comparable, suggesting that vocoder simulations with carefully selected parameters can provide a good estimate of how prosody may be identified by CI users.

CONCLUSIONS

The meta-analysis revealed a robust negative effect of electric hearing, where CIs and vocoder simulations had a similar negative influence on the identification of linguistic and emotional prosody, which seemed mainly due to inadequate transmission of f0 cues through the degraded electric hearing speech signal of CIs and vocoder simulations.

Prosody perception and production by children with cochlear implants

The perception and production of emotional and linguistic (focus) prosody were compared in children with cochlear implants (CI) and normally hearing (NH) peers. Thirteen CI and thirteen hearing-age-matched school-aged NH children were tested, as baseline, on non-verbal emotion understanding, non-word repetition, and stimulus identification and naming. Main tests were verbal emotion discrimination, verbal focus position discrimination, acted emotion production, and focus production. Productions were evaluated by NH adult Dutch listeners. All scores between groups were comparable, except a lower score for the CI group for non-word repetition. Emotional prosody perception and production scores correlated weakly for CI children but were uncorrelated for NH children. In general, hearing age weakly predicted emotion production but not perception. Non-verbal emotional (but not linguistic) understanding predicted CI children's (but not controls') emotion perception and production. In conclusion, increasing time in sound might facilitate vocal emotional expression, possibly requiring independently maturing emotion perception skills.