Concurrent-vowel and tone recognitions in acoustic and simulated electric hearing.
Because of the poor spectral resolution in cochlear implants (CIs), fundamental frequency (F0) cues are not well preserved. Chinese-speaking CI users may have great difficulty understanding speech produced by competing talkers, due to conflicting tones. In this study, normal-hearing listeners' concurrent Chinese syllable recognition was measured with unprocessed speech and CI simulations. Concurrent syllables were constructed by summing two vowels from a male talker (with identical mean F0's) or one vowel from each of a male and a female talker (with a relatively large F0 separation). CI signal processing was simulated using four- and eight-channel noise-band vocoders; the degraded spectral resolution may limit listeners' ability to utilize talker and/or tone differences. The results showed that concurrent speech recognition was significantly poorer with the CI simulations than with unprocessed speech. There were significant interactions between the talker and speech-processing conditions, e.g., better tone and syllable recognitions with the male-female condition for unprocessed speech, and with the male-male condition for eight-channel speech. With the CI simulations, competing tones interfered with concurrent-tone and syllable recognitions, but not vowel recognition. Given limited pitch cues, subjects were unable to use F0 differences between talkers or tones for concurrent Chinese syllable recognition.
Luo
Xin
X
Communication and Auditory Neuroscience, House Ear Institute, 2100 West Third Street, Los Angeles, California 90057, USA. luo5@purdue.edu
Fu
Qian-Jie
QJ
D000161:Acoustic Stimulation; D000704:Analysis of Variance; D003054:Cochlear Implants; D005260:Female; D006801:Humans; D008297:Male; D010470:Perceptual Masking; D010700:Phonetics; D013018:Sound Spectrography; D013060:Speech; D013061:Speech Acoustics; D013067:Speech Perception; D013647:Task Performance and Analysis