Background: The accurate perception of prosody assists a listener in deriving meaning from natural speech. Few studies have addressed the ability of cochlear implant (CI) listeners to perceive the brief duration prosodic cues involved in contrastive vowel length, word stress, and compound word and phrase identification.
Purpose: To compare performance in the perception of brief duration prosodic contrasts by CI participants and a control group of normal hearing participants. This study investigated the ability to perceive these cues in quiet and noise conditions, and to identify auditory perceptual factors that might predict prosodic perception in the CI group. Prosodic perception was studied both in noise and quiet because noise is a pervasive feature of everyday environments.
Research Design: A quasi-experimental correlation design was employed.
Study Sample: Twenty-one CI recipients participated along with a control group of 10 normal hearing participants. All CI participants were unilaterally implanted adults who had considerable experience with oral language prior to implantation.
Data Collection and Analysis: Speech identification testing measured the participants' ability to identify word stress, vowel length, and compound words or phrases all of which were presented with minimal-pair response choices. Tests were performed in quiet and in speech-spectrum shaped noise at a 10 dB signal-to-noise ratio. Also, discrimination thresholds for four acoustic properties of a synthetic vowel were measured as possible predictors of prosodic perception. Testing was carried out during one session, and participants used their clinically assigned speech processors.
Results: The CI group could not identify brief prosodic cues as well as the control group, and their performance decreased significantly in the noise condition. Regression analysis showed that the discrimination of intensity predicted performance on the prosodic tasks. The performance decline measured with the older participants meant that age also emerged as a predictor.
Conclusions: This study provides a portrayal of CI recipients' ability to perceive brief prosodic cues. This is of interest in the preparation of rehabilitation materials used in training and in developing realistic expectations for potential CI candidates.
Key Words
Cochlear implants - speech acoustics - speech intelligibility
