FO processing and the separation of competing speech signals by listeners with normal hearing and with hearing loss

Normal-hearing and hearing-impaired listeners were tested to determine F0 d ifference limens For synthetic tokens of 5 steady-state vowels. The same st imuli were then used in a concurrent-vowel labeling task with the F0 differ ence between concurrent vowels ranging between 0 and 4 semitones. Finally, speech recognition was tested for synthetic sentences in the presence of a competing synthetic voice with the same, a higher, or a lower F0. Normal-he aring listeners and hearing-impaired listeners with small F0-discrimination (Delta F0) thresholds showed improvements in vowel labeling when there wer e differences in F0 between vowels on the concurrent-vowel task. Impaired l isteners with high Delta F0 thresholds did not benefit from F0 differences between vowels. At the group level, normal-hearing listeners benefited more than hearing-impaired listeners from F0 differences between competing sign als on both the concurrent-vowel and sentence tasks. However, for individua l listeners, Delta F0 thresholds and improvements in concurrent-vowel label ing based on F0 differences were only weakly associated With F0-based impro vements in performance on the sentence task. For both the concurrent-vowel and sentence tasks, there was evidence that the ability to benefit from F0 differences between competing signals decreases with age.