Construction and evaluation of the Mandarin Chinese matrix (CMNmatrix) sentence test for the assessment of speech recognition in noise.

OBJECTIVE: Development of the Mandarin Chinese matrix (CMNmatrix) sentence test for speech intelligibility measurements in noise according to the international standard procedure. DESIGN: A 50-word base matrix representing the distribution of phonemes and lexical tones of spoken Mandarin was established. Hundred sentences capturing all the co-articulations of two consecutive words were recorded. Word-specific speech recognition functions, speech reception thresholds (SRT: signal-to-noise ratio (SNR), that provides 50% speech intelligibility) and slopes were obtained from measurements at fixed SNRs. The speech material was homogenised in intelligibility by applying level corrections up to ± 2 dB. Subsequently, the CMNmatrix test was evaluated, the comparability of test lists was measured at two fixed SNRs. To investigate the training effect and establish the reference data, speech recognition was measured adaptively. STUDY SAMPLE: Overall, the study sample contained 80 normal-hearing native Mandarin-speaking listeners. RESULTS: Multi-centre evaluation measurements confirmed that test lists are equivalent in intelligibility, with a mean SRT of -10.1 ± 0.1 dB SNR and a slope of 13.1 ± 0.9 %/dB. The reference SRT is -9.3 ± 0.8 and -11.2 ± 1.2 dB SNR for the open- and closed-set response format, respectively. CONCLUSION: The CMNmatrix test is suitable for accurate and internationally comparable speech recognition measurements in noise.

Assessing the Importance of Lexical Tone Contour to Sentence Perception in Mandarin-Speaking Children With Normal Hearing.

Purpose: The aim of the present study was to evaluate the influence of lexical tone contour and age on sentence perception in quiet and in noise conditions in Mandarin-speaking children ages 7 to 11 years with normal hearing. Method: Test materials were synthesized Mandarin sentences, each word with a manipulated lexical contour, that is, normal contour, flat contour, or a tone contour randomly selected from the four Mandarin lexical tone contours. A convenience sample of 75 Mandarin-speaking participants with normal hearing, ages 7, 9, and 11 years (25 participants in each age group), was selected. Participants were asked to repeat the synthesized speech in quiet and in speech spectrum-shaped noise at 0 dB signal-to-noise ratio. Results: In quiet, sentence recognition by the 11-year-old children was similar to that of adults, and misrepresented lexical tone contours did not have a detrimental effect. However, the performance of children ages 9 and 7 years was significantly poorer. The performance of all three age groups, especially the younger children, declined significantly in noise. Conclusions: The present research suggests that lexical tone contour plays an important role in Mandarin sentence recognition, and misrepresented tone contours result in greater difficulty in sentence recognition in younger children. These results imply that maturation and/or language use experience play a role in the processing of tone contours for Mandarin speech understanding, particularly in noise.

Speech perception in Mandarin-speaking children with cochlear implants: A systematic review.

OBJECTIVE: This paper reviewed the literature on the trajectories and the factors significantly affecting post-implantation speech perception development in Mandarin-speaking children with cochlear implants (CIs). DESIGN: A systematic literature search of textbooks and peer-reviewed published journal articles in online bibliographic databases was conducted. STUDY SAMPLE: PubMed, Scopus and Wiley online library were searched for eligible studies based on predefined inclusion and exclusion criteria. RESULTS: A total of 14 journal articles were selected for this review. A number of consistent results were found. That is, children with CIs, as a group, exhibited steep improvement in early speech perception, from exhibiting few prelingual auditory behaviours before implantation to identifying sentences in noise after one year of CI use. After one to three years of CI use, children are expected to identify tones above chance and recognition of words in noise. In addition, early age at implantation, longer duration of CI use and higher maternal education level contributed to greater improvements in speech perception. CONCLUSIONS: Findings from this review will contribute to the establishment of appropriate short-term developmental goals for Mandarin-speaking children with CIs in mainland China and clinicians could use them to determine whether children have made appropriate progress with CIs.

Effects of lexical tone contour on Mandarin sentence intelligibility.

PURPOSE: This study examined the effects of lexical tone contour on the intelligibility of Mandarin sentences in quiet and in noise. METHOD: A text-to-speech synthesis engine was used to synthesize Mandarin sentences with each word carrying the original lexical tone, flat tone, or a tone randomly selected from the 4 Mandarin lexical tones. The synthesized speech signals were presented to 11 normal-hearing listeners for recognition in quiet and in speech-shaped noise at 0 dB signal-to-noise ratio. RESULTS: Normal-hearing listeners nearly perfectly recognized the Mandarin sentences produced with modified tone contours in quiet; however, performance declined substantially in noise. CONCLUSIONS: Consistent with previous findings to some extent, the present findings suggest that lexical tones are relatively redundant cues for Mandarin sentence intelligibility in quiet and that other cues could compensate for the distorted lexical tone contour. However, in noise, the results provide direct evidence that lexical tone contour is important for the recognition of Mandarin sentences.

Assessing the perceptual contributions of vowels and consonants to Mandarin sentence intelligibility.

This study investigated the perceptual contributions of vowels and consonants to Mandarin sentence intelligibility. Mandarin sentences were edited using a noise-replacement paradigm to preserve various amounts of segmental information and presented to normal-hearing listeners to recognize. The vowel-only Mandarin sentences yielded a remarkable 3:1 intelligibility advantage over the consonant-only sentences. This advantage is larger than that obtained with English sentences, suggesting that vowels may have a greater contribution to sentence intelligibility in Mandarin than in English. Although providing information redundant to contributions from vowel centers, a little vowel-consonant boundary transition would significantly improve the intelligibility of the consonant-only Mandarin sentences.

The contribution of matched envelope dynamic range to the binaural benefits in simulated bilateral electric hearing.

PURPOSE: This study examined the effects of envelope dynamic-range mismatch on the intelligibility of Mandarin speech in noise by simulated bilateral electric hearing. METHOD: Noise-vocoded Mandarin speech, corrupted by speech-shaped noise at 5 and 0 dB signal-to-noise ratios, was presented unilaterally or bilaterally to 10 normal-hearing listeners for recognition. For unilateral conditions, the right ear was presented with the 8-channel noise-vocoded stimuli generated using a 15-dB envelope dynamic range (DR). To simulate the envelope DR mismatch between the 2 ears, the left ear was presented with the 8-channel noise-vocoded stimuli generated using a 5-, 10-, or 15-dB envelope DR, respectively. RESULTS: Significant binaural summation benefits for Mandarin speech recognition were observed only with matched envelope DR between the 2 ears. With reduced DR, the performance of tone identification was more consistent in the steady-state speech-shaped noise than that of sentence recognition. CONCLUSIONS: Consistent with previous findings, the present results suggest that Mandarin speech-perception performance of bilateral electric listening in noise is affected by the difference of envelope DR between the 2 implanted ears, and the binaural summation benefits are maximized when DR mismatch is minimized between the 2 implanted ears.

Hearing-aid assembly management among adults from culturally and linguistically diverse backgrounds: toward the feasibility of self-fitting hearing aids.

OBJECTIVE: The purpose of the study was twofold: (1) to assess the ability of hearing-impaired adults in the developing world to independently and accurately assemble a pair of hearing aids by following instructions that were written and illustrated according to best-practice health literacy principles; and (2) to determine which factors influence independent and accurate task completion. DESIGN: Correlational study. STUDY SAMPLE: Forty South African and 40 Chinese adults with a hearing loss and their partners. The participant group included 42 females and 38 males ranging in age from 32 to 92 years. RESULTS: Ninety-five percent of South African and 60% of Chinese participants completed the assembly task, either on their own or with assistance from their partners. Better health literacy, younger age, and a more prestigious occupation were significantly associated with independent task completion for the South African and Chinese participants. Task accuracy was significantly linked to higher levels of cognitive function among South African participants, while a paucity of valid data prevented an analysis of accuracy from being conducted with the Chinese data. CONCLUSION: Individuals of diverse backgrounds can manage the self-fitting hearing-aid assembly task as long as health literacy levels and cultural differences are considered.

Characterization of speech understanding in various types of noise.

This study examined (1) the effects of noise on speech understanding and (2) whether performance in real-life noises could be predicted based on performance in steady-state speech-spectrum-shaped noise. The noise conditions included a steady-state speech-spectrum-shaped noise and six types of real-life noise. Thirty normal-hearing adults were tested using sentence materials from the Cantonese Hearing In Noise Test (CHINT). To achieve the first aim, the performance-intensity function slopes in these noise conditions were estimated and compared. Variations in performance-intensity function slopes were attributed to differences in the amount of amplitude fluctuations and the presence of competing background speech. How well the data obtained in real-life noises fit the performance-intensity functions obtained in steady-state speech-spectrum-shaped noises was examined for the second aim of the study. Four out of six types of noise yielded performance-intensity function slopes similar to that in steady-state speech-spectrum-shaped noise. After accounting for individual differences in sentence reception threshold (SRT) and the offset between the signal-to-noise ratio for 50% intelligibility across different types of noise, performance in steady-state speech-spectrum-shaped noise was found to predict well the performance in most of the real-life noise conditions.

The effects of binaural spectral resolution mismatch on Mandarin speech perception in simulated electric hearing.

This study assessed the effects of binaural spectral resolution mismatch on the intelligibility of Mandarin speech in noise using bilateral cochlear implant simulations. Noise-vocoded Mandarin speech, corrupted by speech-shaped noise at 0 and 5 dB signal-to-noise ratios, were presented unilaterally or bilaterally to normal-hearing listeners with mismatched spectral resolution between ears. Significant binaural benefits for Mandarin speech recognition were observed only with matched spectral resolution between ears. In addition, the performance of tone identification was more robust to noise than that of sentence recognition, suggesting factors other than tone identification might account more for the degraded sentence recognition in noise.

Development of the Cantonese Hearing In Noise Test (CHINT).

OBJECTIVE: To develop a Cantonese version of the Hearing In Noise Test (CHINT) with the same features as the English Hearing In Noise Test (HINT) (Nilsson, Soli, & Sullivan, 1994). DESIGN: The CHINT was developed in five separate studies: (1) evaluation of initial materials; (2) creation of sentence materials; (3) equalization of sentence difficulty; (4) creation of sentence lists; and (5) evaluation of response variability, inter-list reliability, and establishment of norms. Using the CHINT material, reception thresholds for sentences were measured under four headphone test conditions: Quiet, and in noise with noise simulated as originating from 0 degrees (noise front), 90 degrees (noise right), and 270 degrees (noise left). The speech source was located at 0 degrees in all conditions. The locations of the speech and noise sources were simulated using virtual audio processing, as with the English HINT. The noise conditions consisted of listening with noise fixed at 65 dBA with the level of speech varied in an adaptive procedure. A total of 142 subjects with normal hearing thresholds participated in the five studies. RESULTS: Two versions of the test materials, twenty-four 10-sentence lists and twelve 20-sentence lists, were created from a single set of 240 sentences containing 10 syllables per sentence. Using the twenty-four 10-sentence lists, mean thresholds under earphones in quiet were measured at 19.4 dBA and reception thresholds for sentences of -3.9 dB for noise front, -10.6 dB for noise right, and -10.5 dB for noise left. Similar results were obtained using the 20-sentence lists (19.4, -4.0, -10.9, and -11.0 dB, respectively, for quiet, noise front, noise right, and noise left conditions). There was low response variability within each list. High inter-list reliability suggests that consistent results could be obtained using any list. Confidence intervals are reported. The CHINT norms for listening in quiet and noise conditions were comparable to those for the English HINT. CONCLUSIONS: The CHINT is the first standardized Cantonese sentence speech intelligibility test. The CHINT was developed using the same rationale as the English HINT, allowing norm reference results from the two tests to be compared directly across languages. Results showed the CHINT is a reliable test. The CHINT would benefit from further evaluation of validity.

Tone perception of Cantonese-speaking prelingually hearing-impaired children with cochlear implants.

OBJECTIVE: To evaluate tone perception performance in Cantonese-speaking prelingually hearing-impaired children with cochlear implants. STUDY DESIGN AND SETTING: The ability to discriminate and identify Cantonese tones was evaluated on 17 native Cantonese-speaking prelingually hearing-impaired children. Performance was correlated to factors like age of implantation and general communication ability. RESULTS: Subjects' performance in discrimination and identification tasks was slightly above chance level. Although variations in the contour fundamental frequency of the tones provided some cues for tone discrimination, these distinctions proved insufficient for subjects to perform well. Tone 6 (low level tone) was the most difficult to identify. Subjects' performance did not correlate with gender, age of implantation, duration of implant use, frequency of auditory training session, or general communication ability. CONCLUSION: Although some children were able to discriminate and/or identify Cantonese tones, their performance was poor. Further studies are needed to understand how tone perception relate to daily speech understanding. SIGNIFICANCE: Cochlear implant speech coding strategies may need modification to optimize tone perception.