Combination and Comparison of Sound Coding Strategies Using Cochlear Implant Simulation With Mandarin Speech

Three cochlear implant (CI) sound coding strategies were combined in the same signal processing path and compared for speech intelligibility with vocoded Mandarin sentences. The three CI coding strategies, biologically-inspired hearing aid algorithm (BioAid), envelope enhancement (EE), and fundamental frequency modulation (F0mod), were combined with the advanced combination encoder (ACE) strategy. Hence, four singular coding strategies and four combinational coding strategies were derived. Mandarin sentences with speech-shape noise were processed using these coding strategies. Speech understanding of vocoded Mandarin sentences was evaluated using short-time objective intelligibility (STOI) and subjective sentence recognition tests with normal-hearing listeners. For signal-to-noise ratios at 5 dB or above, the EE strategy had slightly higher average scores in both STOI and listening tests compared to ACE. The addition of EE to BioAid slightly increased the mean scores for BioAid+EE, which was the combination strategy with the highest scores in both objective and subjective speech intelligibility. The benefits of BioAid, F0mod, and the four combinational coding strategies were not observed in CI simulation. The findings of this study may be useful for the future design of coding strategies and related studies with Mandarin.

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.

Evaluation of Mandarin Chinese Speech Recognition in Adults with Cochlear Implants Using the Spectral Ripple Discrimination Test

Background

The aim of this study was to explore the value of the spectral ripple discrimination test in speech recognition evaluation among a deaf (post-lingual) Mandarin-speaking population in China following cochlear implantation.

Material/Methods

The study included 23 Mandarin-speaking adult subjects with normal hearing (normal-hearing group) and 17 deaf adults who were former Mandarin-speakers, with cochlear implants (cochlear implantation group). The normal-hearing subjects were divided into men (n=10) and women (n=13). The spectral ripple discrimination thresholds between the groups were compared. The correlation between spectral ripple discrimination thresholds and Mandarin speech recognition rates in the cochlear implantation group were studied.

Results

Spectral ripple discrimination thresholds did not correlate with age (r=−0.19; p=0.22), and there was no significant difference in spectral ripple discrimination thresholds between the male and female groups (p=0.654). Spectral ripple discrimination thresholds of deaf adults with cochlear implants were significantly correlated with monosyllabic recognition rates (r=0.84; p=0.000).

Conclusions

In a Mandarin Chinese speaking population, spectral ripple discrimination thresholds of normal-hearing individuals were unaffected by both gender and age. Spectral ripple discrimination thresholds were correlated with Mandarin monosyllabic recognition rates of Mandarin-speaking in post-lingual deaf adults with cochlear implants. The spectral ripple discrimination test is a promising method for speech recognition evaluation in adults following cochlear implantation in China.

The Effect of Dialect on Speech Audiometry Testing

Purpose

In this study, the authors examined the validity of using materials from 2 nonregional yet mutually intelligible dialects to evaluate an individual's speech recognition threshold (SRT) and word recognition (WR) abilities and whether a speaker of 1 dialect could accurately administer and score materials in the other dialect.

Method

Previously created SRT and WR materials were presented to 32 Mandarin listeners with normal hearing: 16 speakers of Mainland Mandarin and 16 speakers of Taiwan Mandarin. Hearing abilities were examined using SRT and WR materials created for speakers from 2 different regional dialects. Presentation of the materials occurred during 2 test sessions, counterbalanced across material and listener dialect. Listener responses were evaluated by 2 judges; 1 spoke Mainland Mandarin, and the other spoke Taiwan Mandarin.

Results

For the SRT and WR results, differences in listener performance were statistically significant across material and listener dialect, with threshold differences of less than 2 dB HL when collapsed across session. The interscorer percentage of agreement was 99.5% for SRT and 99.1% for WR testing.

Conclusion

Testing with materials in a different regional dialect does have a measurable impact on SRT and WR performance. However, this difference, though reliable, is small enough to have a negligible impact on clinical findings.

Performance-Intensity Functions of Mandarin Word Recognition Tests in Noise: Test Dialect and Listener Language Effects

Purpose

This study established the performance-intensity function for Beijing and Taiwan Mandarin bisyllabic word recognition tests in noise in native speakers of Wu Chinese. Effects of the test dialect and listeners' first language on psychometric variables (i.e., slope and 50%-correct threshold) were analyzed.

Method

Thirty-two normal-hearing Wu-speaking adults who used Mandarin since early childhood were compared to 16 native Mandarin-speaking adults. Both Beijing and Taiwan bisyllabic word recognition tests were presented at 8 signal-to-noise ratios (SNRs) in 4-dB steps (−12 dB to +16 dB). At each SNR, a half list (25 words) was presented in speech-spectrum noise to listeners' right ear. The order of the test, SNR, and half list was randomized across listeners. Listeners responded orally and in writing.

Results

Overall, the Wu-speaking listeners performed comparably to the Mandarin-speaking listeners on both tests. Compared to the Taiwan test, the Beijing test yielded a significantly lower threshold for both the Mandarin- and Wu-speaking listeners, as well as a significantly steeper slope for the Wu-speaking listeners.

Conclusion

Both Mandarin tests can be used to evaluate Wu-speaking listeners. Of the 2, the Taiwan Mandarin test results in more comparable functions across listener groups. Differences in the performance-intensity function between listener groups and between tests indicate a first language and dialectal effect, respectively.