Development and validation of the Mandarin disyllable recognition test

Cortical responses correlate with speech performance in pre-lingually deaf cochlear implant children

Introduction

Cochlear implantation is currently the most successful intervention for severe-to-profound sensorineural hearing loss, particularly in deaf infants and children. Nonetheless, there remains a significant degree of variability in the outcomes of CI post-implantation. The purpose of this study was to understand the cortical correlates of the variability in speech outcomes with a cochlear implant in pre-lingually deaf children using functional near-infrared spectroscopy (fNIRS), an emerging brain-imaging technique.

Methods

In this experiment, cortical activities when processing visual speech and two levels of auditory speech, including auditory speech in quiet and in noise with signal-to-noise ratios of 10 dB, were examined in 38 CI recipients with pre-lingual deafness and 36 normally hearing children whose age and sex matched CI users. The HOPE corpus (a corpus of Mandarin sentences) was used to generate speech stimuli. The regions of interest (ROIs) for the fNIRS measurements were fronto-temporal-parietal networks involved in language processing, including bilateral superior temporal gyrus, left inferior frontal gyrus, and bilateral inferior parietal lobes.

Results

The fNIRS results confirmed and extended findings previously reported in the neuroimaging literature. Firstly, cortical responses of superior temporal gyrus to both auditory and visual speech in CI users were directly correlated to auditory speech perception scores, with the strongest positive association between the levels of cross-modal reorganization and CI outcome. Secondly, compared to NH controls, CI users, particularly those with good speech perception, showed larger cortical activation in the left inferior frontal gyrus in response to all speech stimuli used in the experiment.

Discussion

In conclusion, cross-modal activation to visual speech in the auditory cortex of pre-lingually deaf CI children may be at least one of the neural bases of highly variable CI performance due to its beneficial effects for speech understanding, thus supporting the prediction and assessment of CI outcomes in clinic. Additionally, cortical activation of the left inferior frontal gyrus may be a cortical marker for effortful listening.

Development of the Mandarin Nonsense Word Identification Test

OBJECTIVE

This study aimed to develop a digitised Mandarin Nonsense Word Speech Perception Test for use in Malaysia, a multilingual country in Southeast Asia.

DESIGN

In Phase I, 400 vowel-consonant-vowel (VCV) nonsense word samples containing 20 Mandarin consonants in /a/, /i/, or /u/ contexts were recorded from two speakers of different genders. Acoustic analyses, sound quality ratings, and item validations were used to guide selection of items to form two gender-specific test lists. In Phase II, performance-intensity functions and test-retest reliability for the lists were established.

STUDY SAMPLE

Native Mandarin-speaking adults with normal hearing participated in Phase I (n = 10) and Phase II (n = 69).

RESULTS

Eighty-four of the 400 VCV words were selected to form two gender-specific test lists. A two-way repeated measure ANOVA revealed a significant interaction effect between speaker-gender and presentation level [F (4.88, 283.20) = 22.79, p < 0.001, η_p²= 0.28]. Intraclass correlation scores of 0.75 and 0.87 were obtained for the female-speaker and male-speaker lists respectively.

CONCLUSIONS

The preliminary normative data of the Mandarin nonsense word test have been developed. It is recommended to use separate gender-specific norms when conducting the test. The test has good validity and reliability for testing Mandarin-speaking adults in Malaysia.

A review of Mandarin speech recognition test materials for use in Singapore

OBJECTIVE

This study aimed to evaluate word lists of current Mandarin speech recognition test materials on their adaptability for use on adult Singapore Mandarin speakers.

DESIGN

This scoping review involved literature search through electronic databases for studies published in English or Mandarin, detailing the development or validation of Mandarin speech recognition test materials meant to be used in quiet. Word lists of materials were evaluated for phonemic balance (Stage 1) and familiarity to Singapore Mandarin speakers by comparing the test items against a list of 1,000 common Singapore Mandarin words (Stage 2).

STUDY SAMPLE

Thirty articles that fulfilled the inclusion and exclusion criteria were reviewed.

RESULTS

Nine sets of materials were found and evaluated in Stage 1. Among these, two sets of materials did not contain phonemically balanced word lists. The remaining seven sets of materials were evaluated in Stage 2. The percentage of unfamiliar characters to Singapore Mandarin speakers was found to be between 15% and 41% across the word lists.

CONCLUSION

None of the currently available materials contain word lists that can be readily adapted for re-recording with the voice of a Singapore Mandarin speaker. There is a need to develop original Singapore Mandarin speech recognition test materials.

Music Training Can Improve Music and Speech Perception in Pediatric Mandarin-Speaking Cochlear Implant Users

Due to limited spectral resolution, cochlear implants (CIs) do not convey pitch information very well. Pitch cues are important for perception of music and tonal language; it is possible that music training may improve performance in both listening tasks. In this study, we investigated music training outcomes in terms of perception of music, lexical tones, and sentences in 22 young (4.8 to 9.3 years old), prelingually deaf Mandarin-speaking CI users. Music perception was measured using a melodic contour identification (MCI) task. Speech perception was measured for lexical tones and sentences presented in quiet. Subjects received 8 weeks of MCI training using pitch ranges not used for testing. Music and speech perception were measured at 2, 4, and 8 weeks after training was begun; follow-up measures were made 4 weeks after training was stopped. Mean baseline performance was 33.2%, 76.9%, and 45.8% correct for MCI, lexical tone recognition, and sentence recognition, respectively. After 8 weeks of MCI training, mean performance significantly improved by 22.9, 14.4, and 14.5 percentage points for MCI, lexical tone recognition, and sentence recognition, respectively (p < .05 in all cases). Four weeks after training was stopped, there was no significant change in posttraining music and speech performance. The results suggest that music training can significantly improve pediatric Mandarin-speaking CI users’ music and speech perception.

Bilaterally Combined Electric and Acoustic Hearing in Mandarin-Speaking Listeners: The Population With Poor Residual Hearing

The hearing loss criterion for cochlear implant candidacy in mainland China is extremely stringent (bilateral severe to profound hearing loss), resulting in few patients with substantial residual hearing in the nonimplanted ear. The main objective of the current study was to examine the benefit of bimodal hearing in typical Mandarin-speaking implant users who have poorer residual hearing in the nonimplanted ear relative to those used in the English-speaking studies. Seventeen Mandarin-speaking bimodal users with pure-tone averages of ∼80 dB HL participated in the study. Sentence recognition in quiet and in noise as well as tone and word recognition in quiet were measured in monaural and bilateral conditions. There was no significant bimodal effect for word and sentence recognition in quiet. Small bimodal effects were observed for sentence recognition in noise (6%) and tone recognition (4%). The magnitude of both effects was correlated with unaided thresholds at frequencies near voice fundamental frequencies (F0s). A weak correlation between the bimodal effect for word recognition and unaided thresholds at frequencies higher than F0s was identified. These results were consistent with previous findings that showed more robust bimodal benefits for speech recognition tasks that require higher spectral resolution than speech recognition in quiet. The significant but small F0-related bimodal benefit was also consistent with the limited acoustic hearing in the nonimplanted ear of the current subject sample, who are representative of the bimodal users in mainland China. These results advocate for a more relaxed implant candidacy criterion to be used in mainland China.

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

OBJECTIVE

The objective of this study was to examine whether cochlear implantation using the round window (RW) route versus cochleostomy achieves comparable electrode impedance and hearing results.

METHODS

This retrospective analysis included 40 patients receiving a cochlear implant (REZ-1): 20 using the RW approach and the remaining 20 using cochleostomy. Electrode impedance and tone, vowel, consonant, disyllable and sentence perception were measured during and after the implantation.

RESULTS

Electrode impedance did not differ significantly between the 2 groups at any time points [F(1, 38) = 1.84; p = 0.184]: 1.87, 5.16, 6.47 and 6.70 kΩ in the RW group versus 2.86, 5.33, 6.92 and 8.16 kΩ in the cochleostomy group at 0, 1, 3 and 12 months, respectively. There was no significant difference between the RW and cochleostomy groups for tone (77.50 vs. 80.50%; p = 0.472), vowel (77.70 vs. 78.65%; p = 0.760), consonant (75.50 vs. 78.25%; p = 0.443), disyllable (78.60 vs. 81.50%; p = 0.317) and sentence (50.90 vs. 52.50%; p = 0.684) perception at 12 months.

CONCLUSION

The RW approach is comparable to cochleostomy in electrode placement as reflected by impedance and function as reflected by tone, vowel, consonant, disyllable and sentence perception.

The Benefits of Residual Hair Cell Function for Speech and Music Perception in Pediatric Bimodal Cochlear Implant Listeners

Objective

The aim of this study was to investigate the benefits of residual hair cell function for speech and music perception in bimodal pediatric Mandarin-speaking cochlear implant (CI) listeners.

Design

Speech and music performance was measured in 35 Mandarin-speaking pediatric CI users for unilateral (CI-only) and bimodal listening. Mandarin speech perception was measured for vowels, consonants, lexical tones, and sentences in quiet. Music perception was measured for melodic contour identification (MCI).

Results

Combined electric and acoustic hearing significantly improved MCI and Mandarin tone recognition performance, relative to CI-only performance. For MCI, performance was significantly better with bimodal listening for all semitone spacing conditions (p < 0.05 in all cases). For tone recognition, bimodal performance was significantly better only for tone 2 (rising; p < 0.05). There were no significant differences between CI-only and CI + HA for vowel, consonant, or sentence recognition.

Conclusions

The results suggest that combined electric and acoustic hearing can significantly improve perception of music and Mandarin tones in pediatric Mandarin-speaking CI patients. Music and lexical tone perception depends strongly on pitch perception, and the contralateral acoustic hearing coming from residual hair cell function provided pitch cues that are generally not well preserved in electric hearing.

Validation of list equivalency for Mandarin speech materials to use with cochlear implant listeners

OBJECTIVES

Speech materials validated with normal-hearing listeners may not be appropriate for clinical assessment of cochlear implant (CI) users. The aim of this study was to validate list equivalency of the Mandarin Speech Perception (MSP) sentences, disyllables, and monosyllables in Mandarin-speaking CI patients.

DESIGN

Recognition of MSP sentences, disyllables, and monosyllables each were measured for all 10 lists.

STUDY SAMPLE

67 adult and 32 pediatric Mandarin-speaking CI users.

RESULTS

There was no significant difference between adult and pediatric subject groups for all test materials. Significant differences were observed among lists within each test. After removing one or two lists within each test, no significant differences were observed among the remaining lists. While there was equal variance among lists within a given test, the variance was larger for children than for adults, and increased from monosyllables to disyllables to sentences.

CONCLUSIONS

Some adjustment to test lists previously validated with CI simulations was needed to create perceptually equivalent lists for real CI users, suggesting that test materials should be validated in the targeted population. Differences in mean scores and variance across test materials suggest that CI users may differ in their ability to make use of contextual cues available in sentences and disyllables.

Auditory implant research at the House Ear Institute 1989-2013

The House Ear Institute (HEI) had a long and distinguished history of auditory implant innovation and development. Early clinical innovations include being one of the first cochlear implant (CI) centers, being the first center to implant a child with a cochlear implant in the US, developing the auditory brainstem implant, and developing multiple surgical approaches and tools for Otology. This paper reviews the second stage of auditory implant research at House - in-depth basic research on perceptual capabilities and signal processing for both cochlear implants and auditory brainstem implants. Psychophysical studies characterized the loudness and temporal perceptual properties of electrical stimulation as a function of electrical parameters. Speech studies with the noise-band vocoder showed that only four bands of tonotopically arrayed information were sufficient for speech recognition, and that most implant users were receiving the equivalent of 8-10 bands of information. The noise-band vocoder allowed us to evaluate the effects of the manipulation of the number of bands, the alignment of the bands with the original tonotopic map, and distortions in the tonotopic mapping, including holes in the neural representation. Stimulation pulse rate was shown to have only a small effect on speech recognition. Electric fields were manipulated in position and sharpness, showing the potential benefit of improved tonotopic selectivity. Auditory training shows great promise for improving speech recognition for all patients. And the Auditory Brainstem Implant was developed and improved and its application expanded to new populations. Overall, the last 25 years of research at HEI helped increase the basic scientific understanding of electrical stimulation of hearing and contributed to the improved outcomes for patients with the CI and ABI devices. This article is part of a Special Issue entitled .

Contribution of auditory working memory to speech understanding in mandarin-speaking cochlear implant users

PURPOSE

To investigate how auditory working memory relates to speech perception performance by Mandarin-speaking cochlear implant (CI) users.

METHOD

Auditory working memory and speech perception was measured in Mandarin-speaking CI and normal-hearing (NH) participants. Working memory capacity was measured using forward digit span and backward digit span; working memory efficiency was measured using articulation rate. Speech perception was assessed with: (a) word-in-sentence recognition in quiet, (b) word-in-sentence recognition in speech-shaped steady noise at +5 dB signal-to-noise ratio, (c) Chinese disyllable recognition in quiet, (d) Chinese lexical tone recognition in quiet. Self-reported school rank was also collected regarding performance in schoolwork.

RESULTS

There was large inter-subject variability in auditory working memory and speech performance for CI participants. Working memory and speech performance were significantly poorer for CI than for NH participants. All three working memory measures were strongly correlated with each other for both CI and NH participants. Partial correlation analyses were performed on the CI data while controlling for demographic variables. Working memory efficiency was significantly correlated only with sentence recognition in quiet when working memory capacity was partialled out. Working memory capacity was correlated with disyllable recognition and school rank when efficiency was partialled out. There was no correlation between working memory and lexical tone recognition in the present CI participants.

CONCLUSIONS

Mandarin-speaking CI users experience significant deficits in auditory working memory and speech performance compared with NH listeners. The present data suggest that auditory working memory may contribute to CI users' difficulties in speech understanding. The present pattern of results with Mandarin-speaking CI users is consistent with previous auditory working memory studies with English-speaking CI users, suggesting that the lexical importance of voice pitch cues (albeit poorly coded by the CI) did not influence the relationship between working memory and speech perception.