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

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.

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.

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.

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.