Tonal Languages and Cochlear Implants

Reading Comprehension of Chinese-Speaking Children With Hearing Loss: The Roles of Metalinguistic Awareness and Vocabulary Knowledge

PURPOSE

This study aims to explore the contributions of phonological awareness (PA) and morphological awareness (MA) to the reading comprehension skills of Chinese-speaking children with hearing loss (HL) and examine the possible mediation effect of vocabulary knowledge on the relationships of PA and MA with their reading comprehension.

METHOD

The participants were 28 Chinese-speaking children with HL, who were followed from Grade 1 through Grade 2. They were administered a series of tests that measured their PA and MA at the beginning of Grade 1, vocabulary knowledge at the end of Grade 1, and reading comprehension at the end of Grade 2.

RESULTS

MA significantly accounted for additional variance in reading comprehension beyond the effect of PA but not vice versa. Both PA and MA contributed uniquely to vocabulary knowledge, which completely mediated the relationships of PA and MA with reading comprehension.

CONCLUSIONS

PA and MA are both essential to the development of vocabulary knowledge and reading comprehension in Chinese-speaking children with HL; however, MA seems to be more important than PA in their reading comprehension. PA and MA significantly affect children's reading comprehension through their influence on vocabulary knowledge. This study has replicated previous evidence on the importance of PA, MA, and vocabulary knowledge in the reading comprehension of children with typical hearing, and has extended its significance to children with HL. In addition, the findings have the potential to inform educational practitioners regarding the importance of teaching essential reading skills to Chinese-speaking children with HL.

Pre-attentive fundamental frequency processing in Mandarin-speaking children with cochlear implants as revealed by the peak latency of positive mismatch response

Introduction

Fundamental frequency (F0) serves as the primary acoustic cue for Mandarin tone perception. Recent behavioral studies suggest that F0 information may be differently processed between Mandarin-speaking normal-hearing (NH) children and children with cochlear implants (CIs), which may partially explain the unsatisfactory outcome of lexical tone recognition using CIs with tonal language-oriented speech processing strategies. The aim of the current study was to provide neural evidence of F0 processing in Mandarin-speaking kindergarten-aged children with CIs compared with NH children.

Methods

Positive mismatch responses (p-MMRs) to the change of the two acoustic dimensions of F0 (F0 contour and F0 level) in Mandarin-speaking kindergarten-aged children with CIs (n = 19) and their age-matched NH peers (n = 21).

Results

The two groups of children did not show any significant difference on the mean amplitude of p-MMR to either F0 contour or F0 level change. While the CI group exhibited a significantly shorter peak latency of p-MMR to F0 contour change than to F0 level change, an opposite pattern was observed in the NH group.

Discussion

This study revealed a higher sensitivity to F0 contour change than to F0 level change in children with CIs, which was different from that in NH children. The neural evidence of discrepant F0 processing between children with CIs and NH children in this study was consistent with the previously reported behavioral findings and may serve as a reference for the development and improvement of tonal language-oriented speech processing strategies.

Development and Validation of a Mandarin Chinese Adaptation of AzBio Sentence Test (CMnBio)

A new sentence recognition test in Mandarin Chinese was developed and validated following the principles and procedures of development of the English AzBio sentence materials. The study was conducted in two stages. In the first stage, 1,020 sentences spoken by 4 talkers (2 males and 2 females) were processed through a 5-channel noise vocoder and presented to 17 normal-hearing Mandarin-speaking adults for recognition. A total of 600 sentences (150 from each talker) in the range of approximately 62 to 92% correct (mean = 78.0% correct) were subsequently selected to compile 30, 20-sentence lists. In the second stage, 30 adult CI users were recruited to verify the list equivalency. A repeated-measures analysis of variance followed by the post hoc Tukey's test revealed that 26 of the 30 lists were equivalent. Finally, a binomial distribution model was adopted to account for the inherent variability in the lists. It was found that the inter-list variability could be best accounted for with a 65-item binomial distribution model. The lower and upper limits of the 95% critical differences for one- and two-list recognition scores were then generated to provide guidance for detection of a significant difference in recognition scores in clinical settings. The final set of 26 equivalent lists contains sentence materials more difficult than those found in other speech audiometry materials in Mandarin Chinese. This test should help minimize the ceiling effects when testing sentence recognition in Mandarin-speaking CI users.

Mandarin tone recognition training with cochlear implant simulation: Amplitude envelope enhancement and cue weighting

With limited fundamental frequency (F0) cues, cochlear implant (CI) users recognize Mandarin tones using amplitude envelope. This study investigated whether tone recognition training with amplitude envelope enhancement may improve tone recognition and cue weighting with CIs. Three groups of CI-simulation listeners received training using vowels with amplitude envelope modified to resemble F0 contour (enhanced-amplitude-envelope training), training using natural vowels (natural-amplitude-envelope training), and exposure to natural vowels without training, respectively. Tone recognition with natural and enhanced amplitude envelope cues and cue weighting of amplitude envelope and F0 contour were measured in pre-, post-, and retention-tests. It was found that with similar pre-test performance, both training groups had better tone recognition than the no-training group after training. Only enhanced-amplitude-envelope training increased the benefits of amplitude envelope enhancement in the post- and retention-tests than in the pre-test. Neither training paradigm increased the cue weighting of amplitude envelope and F0 contour more than stimulus exposure. Listeners attending more to amplitude envelope in the pre-test tended to have better tone recognition with enhanced amplitude envelope cues before training and improve more in tone recognition after enhanced-amplitude-envelope training. The results suggest that auditory training and speech enhancement may bring maximum benefits to CI users when combined.

The Relative Weight of Temporal Envelope Cues in Different Frequency Regions for Mandarin Disyllabic Word Recognition

Objectives

Acoustic temporal envelope (E) cues containing speech information are distributed across all frequency spectra. To provide a theoretical basis for the signal coding of hearing devices, we examined the relative weight of E cues in different frequency regions for Mandarin disyllabic word recognition in quiet.

Design

E cues were extracted from 30 continuous frequency bands within the range of 80 to 7,562 Hz using Hilbert decomposition and assigned to five frequency regions from low to high. Disyllabic word recognition of 20 normal-hearing participants were obtained using the E cues available in two, three, or four frequency regions. The relative weights of the five frequency regions were calculated using least-squares approach.

Results

Participants correctly identified 3.13-38.13%, 27.50-83.13%, or 75.00-93.13% of words when presented with two, three, or four frequency regions, respectively. Increasing the number of frequency region combinations improved recognition scores and decreased the magnitude of the differences in scores between combinations. This suggested a synergistic effect among E cues from different frequency regions. The mean weights of E cues of frequency regions 1-5 were 0.31, 0.19, 0.26, 0.22, and 0.02, respectively.

Conclusion

For Mandarin disyllabic words, E cues of frequency regions 1 (80-502 Hz) and 3 (1,022-1,913 Hz) contributed more to word recognition than other regions, while frequency region 5 (3,856-7,562) contributed little.

Acoustic Assessment of Tone Production of Prelingually-Deafened Mandarin-Speaking Children With Cochlear Implants

Objective

The purpose of the present study was to investigate Mandarin tone production performance of prelingually deafened children with cochlear implants (CIs) using modified acoustic analyses and to evaluate the relationship between demographic factors of those CI children and their tone production ability.

Methods

Two hundred seventy-eight prelingually deafened children with CIs and 173 age-matched normal-hearing (NH) children participated in the study. Thirty-six monosyllabic Mandarin Chinese words were recorded from each subject. The fundamental frequencies (F0) were extracted from the tone tokens. Two acoustic measures (i.e., differentiability and hit rate) were computed based on the F0 onset and offset values (i.e., the tone ellipses of the two-dimensional [2D] method) or the F0 onset, midpoint, and offset values (i.e., the tone ellipsoids of the 3D method). The correlations between the acoustic measures as well as between the methods were performed. The relationship between demographic factors and acoustic measures were also explored.

Results

The children with CIs showed significantly poorer performance in tone differentiability and hit rate than the NH children. For both CI and NH groups, performance on the two acoustic measures was highly correlated with each other (r values: 0.895–0.961). The performance between the two methods (i.e., 2D and 3D methods) was also highly correlated (r values: 0.774–0.914). Age at implantation and duration of CI use showed a weak correlation with the scores of acoustic measures under both methods. These two factors jointly accounted for 15.4–18.9% of the total variance of tone production performance.

Conclusion

There were significant deficits in tone production ability in most prelingually deafened children with CIs, even after prolonged use of the devices. The strong correlation between the two methods suggested that the simpler, 2D method seemed to be efficient in acoustic assessment for lexical tones in hearing-impaired children. Age at implantation and especially the duration of CI use were significant, although weak, predictors for tone development in pediatric CI users. Although a large part of tone production ability could not be attributed to these two factors, the results still encourage early implantation and continual CI use for better lexical tone development in Mandarin-speaking pediatric CI users.

Mandarin lexical tone recognition in bimodal cochlear implant users

Objective: To assess the recognition of lexical tones in Mandarin-speaking bimodal cochlear implant (CI) subjects.Design: Lexical tone recognition in quiet and noise (SNR= +5 dB) was measured with electric stimulation (CI alone) or bimodal stimulation (CI + hearing aid (HA)). The recognition and confusion rates of the four tones (T1, T2, T3 and T4) were analysed. Spearman correlation analysis was performed to examine the relationship between hearing levels in the contralateral ear and bimodal benefits.Study sample: Twenty native Mandarin-speaking bimodal CI users, with ages ranging from 16-49 years.Results: Relative to the CI alone, mean tone recognition with the CI + HA improved significantly from 84.1-92.1% correct in quiet (+8 points) and from 57.9-73.1% correct in noise (+15.2 points). Tone confusions between T2 and T3 were the most prominent in all test conditions, and T4 tended to be labelled as T3 in noise. There was no significant correlation between the bimodal benefits for tone recognition and the unaided or HA-aided pure-tone thresholds at 0.25 kHz.Conclusion: Listeners with CI + HA exhibited significantly better tone recognition than with CI alone. The bimodal advantage for tone recognition was greater in noise than in quiet, perhaps due to a ceiling effect in quiet.

Contributions of lexical tone to Mandarin sentence recognition in hearing-impaired listeners under noisy conditions

Mandarin sentence recognition using natural-tone and flat-tone sentences was tested in 22 subjects with sensorineural hearing loss (SNHL) and 25 listeners with normal hearing (NH) in quiet, speech-shaped noise, and two-talker-babble conditions. While little effects of flat tones on sentence recognition were seen in the NH listeners when the signal-to-noise ratio (SNR) was ≥0 dB, the SNHL listeners showed decreases in flat-tone-sentence recognition in quiet and at +5-dB SNR. Such declined performance was correlated with their degrees of hearing loss. Lexical tone contributes greatly to sentence recognition in hearing-impaired listeners in both quiet and in noise listening conditions.

Singing Proficiency of Members of a Choir Formed by Prelingually Deafened Children With Cochlear Implants

Purpose A group of 10 prelingually deafened children with cochlear implants (CIs) formed a choir and received 21 months of formal music training. The purpose of this study was to evaluate the singing proficiency of these children. Method The participants included all choir members (7 girls and 3 boys, mean age of 9.5 years old) who were unilateral CI users. Meanwhile, 8 age-matched children with normal hearing were recruited as controls and were trained on 1 song for 2 weeks. Individual singing samples without instrument accompaniment were recorded from all participants. The singing samples were subject to acoustic analysis in which the fundamental frequency (F0) of each note was extracted and the duration was measured. Five metrics were developed and computed to quantify the accuracy of their pitch and rhythm performance. The 5 metrics included (a) percent correct of F0 contour direction of adjacent notes, (b) mean deviation of the normalized F0 across the notes, (c) mean deviation of the pitch intervals, (d) mean deviation of adjacent note duration ratio, and (e) mean absolute deviation of note duration. Results The choir members with CIs demonstrated high accuracy in both pitch and tempo measures and performed on par with the children with normal hearing. Early start of music training after implantation and use of bimodal hearing contributed to the development of better music ability in these children with CIs. Conclusion These findings indicated that rigorous music training could facilitate high singing proficiency in prelingually deafened children with CIs.

Categorical perception of lexical tones in native Mandarin-speaking listeners with sensorineural hearing loss

BACKGROUND

Categorical perception (CP) of lexical tones was examined in normal hearing (NH) people, but it was unclear whether lexical tones can be perceived categorically in sensorineural hearing loss (SNHL) people.

OBJECTIVES

To explore the characteristic of lexical tone perception in native Mandarin speakers with SNHL.

MATERIALS AND METHODS

Three types of continuum (Tone1/Tone2, Tone1/Tone4 and Tone2/Tone3) were constructed and each of them includes 15 stimuli which were resynthesized by applying the pitch-synchronous overlap and add (PSOLA) method implemented in Praat to the same Mandarin syllable, /a/, with a high-level tone produced by a female speaker. Forty native Mandarin NH speakers and 23 native Mandarin speakers with mild to moderate SNHL were recruited. A two alternative-forced-choice identification task was used to acquire the tonal perceptual data.

RESULTS

All tone perception curves owns the characteristic of CP in SNHL subjects. All tone perception curves were S-shape in SNHL subjects same as those in NH subjects. No significant difference of each continuum was observed between SNHL and NH.

CONCLUSIONS

CP of lexical tone perception could be observed in native Mandarin speakers with mild to moderate SNHL. The slight damage in the peripheral auditory system did not change characteristic of lexical tone perception.

A Follow-Up Study on Music and Lexical Tone Perception in Adult Mandarin-Speaking Cochlear Implant Users

OBJECTIVE

The aim was to evaluate the development of music and lexical tone perception in Mandarin-speaking adult cochlear implant (CI) users over a period of 1 year.

STUDY DESIGN

Prospective patient series.

SETTING

Tertiary hospital and research institute.

PATIENTS

Twenty five adult CI users, with ages ranging from 19 to 75 years old, participated in a year-long follow-up evaluation. There were also 40 normal hearing adult subjects who participated as a control group to provide the normal value range.

INTERVENTIONS

Musical sounds in cochlear implants (Mu.S.I.C.) test battery was undertaken to evaluate music perception ability. Mandarin Tone Identification in Noise Test (M-TINT) was used to assess lexical tone recognition. The tests for CI users were completed at 1, 3, 6, and 12 months after the CI switch-on.

MAIN OUTCOMES MEASURES

Quantitative and statistical analysis of their results from music and tone perception tests.

RESULTS

The performance of music perception and tone recognition both demonstrated an overall improvement in outcomes during the entire 1-year follow-up process. The increasing trends were obvious in the early period especially in the first 6 months after switch-on. There was a significant improvement in the melody discrimination (p < 0.01), timbre identification (p < 0.001), tone recognition in quiet (p < 0.0001), and in noise (p < 0.0001).

CONCLUSIONS

Adult Mandarin-speaking CI users show an increasingly improved performance on music and tone perception during the 1-year follow-up. The improvement was the most prominent in the first 6 months of CI use. It is essential to strengthen the rehabilitation training within the first 6 months.

Relative contributions of acoustic temporal fine structure and envelope cues for lexical tone perception in noise

Previous studies have shown that lexical tone perception in quiet relies on the acoustic temporal fine structure (TFS) but not on the envelope (E) cues. The contributions of TFS to speech recognition in noise are under debate. In the present study, Mandarin tone tokens were mixed with speech-shaped noise (SSN) or two-talker babble (TTB) at five signal-to-noise ratios (SNRs; -18 to +6 dB). The TFS and E were then extracted from each of the 30 bands using Hilbert transform. Twenty-five combinations of TFS and E from the sound mixtures of the same tone tokens at various SNRs were created. Twenty normal-hearing, native-Mandarin-speaking listeners participated in the tone-recognition test. Results showed that tone-recognition performance improved as the SNRs in either TFS or E increased. The masking effects on tone perception for the TTB were weaker than those for the SSN. For both types of masker, the perceptual weights of TFS and E in tone perception in noise was nearly equivalent, with E playing a slightly greater role than TFS. Thus, the relative contributions of TFS and E cues to lexical tone perception in noise or in competing-talker maskers differ from those in quiet and those to speech perception of non-tonal languages.

Lexical tone recognition in noise in normal-hearing children and prelingually deafened children with cochlear implants

OBJECTIVE

The purpose of the present study was to investigate Mandarin tone recognition in background noise in children with cochlear implants (CIs), and to examine the potential factors contributing to their performance.

DESIGN

Tone recognition was tested using a two-alternative forced-choice paradigm in various signal-to-noise ratio (SNR) conditions (i.e. quiet, +12, +6, 0, and -6 dB). Linear correlation analysis was performed to examine possible relationships between the tone-recognition performance of the CI children and the demographic factors.

STUDY SAMPLE

Sixty-six prelingually deafened children with CIs and 52 normal-hearing (NH) children as controls participated in the study.

RESULTS

Children with CIs showed an overall poorer tone-recognition performance and were more susceptible to noise than their NH peers. Tone confusions between Mandarin tone 2 and tone 3 were most prominent in both CI and NH children except for in the poorest SNR conditions. Age at implantation was significantly correlated with tone-recognition performance of the CI children in noise.

CONCLUSIONS

There is a marked deficit in tone recognition in prelingually deafened children with CIs, particularly in noise listening conditions. While factors that contribute to the large individual differences are still elusive, early implantation could be beneficial to tone development in pediatric CI users.

Results using the OPAL strategy in Mandarin speaking cochlear implant recipients

OBJECTIVE

To evaluate the effectiveness of an experimental pitch-coding strategy for improving recognition of Mandarin lexical tone in cochlear implant (CI) recipients.

DESIGN

Adult CI recipients were tested on recognition of Mandarin tones in quiet and speech-shaped noise at a signal-to-noise ratio of +10 dB; Mandarin sentence speech-reception threshold (SRT) in speech-shaped noise; and pitch discrimination of synthetic complex-harmonic tones in quiet. Two versions of the experimental strategy were examined: (OPAL) linear (1:1) mapping of fundamental frequency (F0) to the coded modulation rate; and (OPAL+) transposed mapping of high F0s to a lower coded rate. Outcomes were compared to results using the clinical ACE™ strategy.

STUDY SAMPLE

Five Mandarin speaking users of Nucleus® cochlear implants.

RESULTS

A small but significant benefit in recognition of lexical tones was observed using OPAL compared to ACE in noise, but not in quiet, and not for OPAL+ compared to ACE or OPAL in quiet or noise. Sentence SRTs were significantly better using OPAL+ and comparable using OPAL to those using ACE. No differences in pitch discrimination thresholds were observed across strategies.

CONCLUSIONS

OPAL can provide benefits to Mandarin lexical tone recognition in moderately noisy conditions and preserve perception of Mandarin sentences in challenging noise conditions.

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.

Music and lexical tone perception in Chinese adult cochlear implant users

OBJECTIVES/HYPOTHESIS

The present study's aim was to assess the music perception ability for Chinese adult cochlear implant users and to investigate the correlation between music and Mandarin-Chinese lexical tone perception.

STUDY DESIGN

Case-control study.

METHODS

Twenty normal-hearing and 21 adult cochlear implant users participated in the Musical Sounds in Cochlear Implants (MuSIC) perception test, including six objective and two subjective musical subtests. The comparison of music perception performance was made between normal-hearing and cochlear implant subjects. Sixteen of the 21 cochlear implant users also performed a tone identification test to investigate the correlation between music and tone perception.

RESULTS

Cochlear implant users performed significantly worse than normal-hearing subjects on pitch discrimination, instrument identification, and instrument detection tests, whereas close to normal-hearing subjects on melody discrimination, chords discrimination, rhythm discrimination, and emotion and dissonance rating subtests. Lexical tone perception was significantly correlated with pitch discrimination, melody discrimination, and instrument identification tests. Duration of hearing aid use was found to be correlated with pitch discrimination ability of cochlear implant users.

CONCLUSIONS

Chinese postlingually deafened cochlear implant users performed significantly poorer in pitch discrimination and timbre perception tasks than normal-hearing listeners. Lexical tone perception was found to be significantly correlated with music pitch perception, supporting the notion that tone and music perception may share a similar pitch perception mechanism.