Mandarin Tone and Vowel Recognition in Cochlear Implant Users: Effects of Talker Variability and Bimodal Hearing

Abstract

Objectives For cochlear implant (CI) users with residual low-frequency acoustic hearing in the non-implanted ear, bimodal hearing combining the use of a CI and a contralateral hearing aid (HA) may provide more salient talker voice cues than CI alone to handle the variability of talker identity across trials. This study tested the effects of talker variability, bimodal hearing, and their interaction on response accuracy and time of CI users’ Mandarin tone, vowel, and syllable recognition (i.e., combined Mandarin tone and vowel recognition in this study). Design Fifteen prelingually deafened native Mandarin-speaking CI users (at age 20 or lower) participated in this study. Four talkers each produced six Mandarin single-vowel syllables in four lexical tones. The stimuli were presented in quiet via a single loudspeaker. To study the effects of talker variability, Mandarin tone, vowel, and syllable recognition was tested in two presentation conditions: with stimuli blocked according to talker (blocked-talker condition) or mixed across talkers from trial to trial (mixed-talker condition). To explore the effects of bimodal hearing, two processor conditions were tested: CI alone or CI+HA. The cumulative response time was recorded as an indirect indicator of the cognitive load or listening effort in each condition. The correlations were computed between demographic/hearing factors (e.g., hearing thresholds in the non-implanted ear) and bimodal performance/benefits (where bimodal benefits refer to the performance differences between CI alone and CI+HA). Results Mandarin tone recognition with both CI alone and CI+HA was significantly poorer in the mixed-talker condition than in the blocked-talker condition, while vowel recognition was comparable in the two presentation conditions. Bimodal hearing significantly improved Mandarin tone recognition but not vowel recognition. Mandarin syllable recognition was significantly affected by both talker variability and bimodal hearing. The cumulative response time significantly reduced with CI+HA compared with CI alone, but remained invariant with respect to talker variability. There was no interaction between talker variability and bimodal hearing for any performance measure adopted in this study. Correlation analyses revealed that the bimodal performance and benefits in Mandarin tone, vowel, and syllable recognition could not be predicted by the hearing thresholds in the non-implanted ear or by the demographic factors of the participants. Conclusions Talker variability from trial to trial significantly degraded Mandarin tone and syllable recognition performance in both the CI alone and CI+HA conditions. While bimodal hearing did not reduce the talker variability effects on Mandarin tone and syllable recognition, generally better Mandarin tone and syllable recognition performance with shorter response time (an indicator of less listening effort) was observed when a contralateral HA was used in conjunction with the CI. On the other hand, vowel recognition was not significantly ...

Comparable Electrode Impedance and Speech Perception at 12 Months after Cochlear Implantation Using Round Window versus Cochleostomy: An Analysis of 40 Patients

“…As can be observed in Figures 3 and 4, the results of tone, vowel, consonant and disyllable perception of the RW and cochleostomy groups were consistent with the previous studies [30][31][32], whereas the sentence perception of those patients was not good, which may be impacted by the different test material and approach. There was a significant difference between the 2 groups 3 months after implantation for the sentence perception, whereas there was no significant difference in tone, vowel, consonant, disyllable and sentence perception of the RW and cochleostomy groups 12 months after implantation.…”

Effects of fundamental frequency contour on understanding Mandarin sentences in bimodal hearing simulations

“…Many early studies assessed the perceptual effect of adding low-frequency acoustic information to electric hearing, and revealed the bimodal benefits in both non-tonal (e.g., Brown and Bacon, 2009;Carroll et al, 2011;Micheyl and Oxenham, 2012) and tonal (e.g., Luo and Fu, 2006;Li et al, 2014;Chang et al, 2016;Yang and Zeng, 2017) languages. As Mandarin Chinese differs with English in terms of the perceptual contribution of F0-contour or tonal information which is largely contained in the low-frequency region, the present work specifically examined the impact of preserving correct tonal information on bimodal benefits in Mandarin sentence perception.…”

“…They tested with the CI-only and CI þ HA conditions, and found combined-stimulation advantage for tone recognition in noise and vowel recognition in quiet, but not for consonant recognition. Chang et al (2016) found that in quiet, Chinese-speaking CI users' tone recognition significantly improved, but their vowel recognition did not significantly change with the use of a HA. The variable benefits of bimodal hearing to Mandarin speech recognition across studies might be due to the different degrees of residual acoustic hearing in individual subjects.…”

“…While a number of works examined the factors affecting English speech understanding in combined electric-and-acoustic stimulation, only a few studies have been done for Chinese speech (e.g., Luo and Fu, 2006;Li et al, 2014;Chang et al, 2016;Yang and Zeng, 2017). With bimodal hearing simulations, Luo and Fu (2006) reported that for CI patients with residual acoustic hearing, preserving low-frequency acoustic information could improve Chinese speech recognition in noise.…”

“…While most CI users are able to perceive sound and understand speech, there are still many challenges for the present CI technology, e.g., understanding a tonal language (e.g., Luo and Fu, 2006;Li et al, 2014;Chang et al, 2016;Yang and Zeng, 2017), speech perception in noise (e.g., Chang et al, 2006), etc. Many hearing-impaired patients preserve some degree of low-frequency (LF) residual hearing and largely suffer from hearing loss at high frequency.…”