Effect of Speaking Rate and Sentence Context on Comprehension and Recognition Memory of Degraded Speech

PURPOSE: Variability in speaking rate and sentence context affects the cognitive processing of speech. Individuals relying on a degraded speech signal may be particularly susceptible to these effects. In this study, we examine how artificial alterations to speaking rates and sentence context affect sentence comprehension and recognition memory for cochlear implant (CI) users and normal-hearing (NH) adults presented with spectrally degraded speech. METHOD: Thirty-seven adult CI users and 71 NH adults participated in the study. Participants completed a sentence verification task paired with a recognition memory task consisting of sentences with artificially manipulated speaking rates and variable sentence context. The sentences presented to NH adults were vocoder processed to simulate CI hearing. Accuracy and response times (RTs) from both the sentence verification task and the sentence recognition memory task were assessed. Logistic and ordinal regression models were constructed to assess the effects of speaking rate and sentence context on the participants' performance. RESULTS: On the sentence verification task, slow sentences had a greater accuracy of sentence comprehension and faster RTs compared to fast sentences, particularly more so for low-context sentences. On the recognition memory task, slow sentences had a greater accuracy of sentence recognition and faster RTs compared to fast sentences. However, the effect of context was less pronounced and actually favored low-context sentences. CI users and older listeners, regardless of hearing status, showed lower overall accuracy and slower RTs. CONCLUSIONS: Speaking rate and sentence context impact sentence comprehension and recognition memory for spectrally degraded speech. Slower speech facilitates processing, especially when contextual support is limited. CI users and older listeners showed slower and more effortful processing. These findings may highlight the importance of speaking rate in effective communication strategies and support theoretical approaches linking increased cognitive effort to the perception of spectrally degraded speech. SUPPLEMENTAL MATERIAL: https://doi.org/10.23641/asha.33179354.