Ai-Ting Chen

Development of a corpus of Mandarin sentences in babble with homogeneity optimized via psychometric evaluation

Abstract Objective: To develop a corpus of sentences in babble noise that is suitable for Mandarin-speaking children. Two experiments were conducted with specific aims of (1) developing sentence material that is grammatically and semantically within the linguistic abilities of children; and (2) improving the efficiency of the test by equalizing the relative intelligibility of individual items in sentences. Design and Study sample: Sentences were extracted from spoken material of Chinese children aged between 4 and 5 years of age. The sentences were tested for intelligibility in a four-talker babble by 96 adult native speakers of Mandarin. Psychometric functions were generated, and used for adjusting signal-to-noise ratios of individual items by varying the level of the time-locked babble to equate intelligibility of the target speech. These adjusted stimuli were tested for intelligibility using a different group of 64 adult listeners. Results: The signal-to-noise ratio for 50% correct was not different before and after adjustments (− 6.1 dB and − 6.0 dB, respectively). However, there was a significant reduction in standard deviation from 2.3 dB before adjustment to 1.1 dB after adjustment (p < 0.05). Conclusions: The experiments established a corpus of Mandarin BKB-like sentences with four-talker babble as competing noise, in which the test items’ homogeneity was optimized via psychometric evaluation (HOPE).

Electrode Interaction in Cochlear Implant Recipients: Comparison of Straight and Contour Electrode Arrays

The degree of overlap among cochlear nerve fibers stimulated by different electrodes results in electrode interaction, which has been shown to have a significantly deleterious effect on speech recognition performance in multi-electrode cochlear implant users. The Nucleus CI24R(CS) Contour array, which lies substantially closer to the modiolus than the CI24M straight array, is expected to exhibit narrower excitation patterns. The neural response telemetry (NRT) 3.0 software provides a method of measuring the spread of neural excitation by presenting the masker and probe pulses on different intra-cochlear electrode bands. Nine pairs of children, using Nucleus CI24M/CI24R(CS) cochlear implants with a similar etiology and duration of deafness, insertion depth, age of implantation and loudest acceptable presentation level (LAPL) in NRT sessions, participated in the study. Profiles of the spread of neural excitation stimulated at the LAPL at 3 probe locations were examined for each pair of the 2 types of electrode array. The spread of neural excitation with respect to array type and location revealed significant effects (p < 0.001; p = 0.002) and no interaction between array type and probe location (p = 0.559). The results demonstrated that the Contour array improved electrode discrimination, especially for the electrodes at the basal end of the cochlea. The findings have implications for future electrode array design and current implant mapping strategies.

Development of a mandarin monosyllable test material with homogenous items (II): Lists equivalence evaluation

Abstract Conclusions: A set of Chinese Mandarin monosyllable test lists with good reliability and sensitivity was established. Objectives. The primary purpose of this study was to evaluate the equivalence of a group of monosyllable lists. Methods: A genetic algorithm was adopted to reorganize the material based on the Phoneme Allocation Table; 10 lists with 25 monosyllabic test items in each were generated. A two-factor design was used for the equivalence evaluation test. A total of 80 normal-hearing and native Mandarin-speaking university students (40 males and 40 females) participated in the trial. Every subject was tested with all 10 lists in sequence at 5 presentation levels (–5, 0, 5, 10, and 15 dB HL). Performance-intensity (P-I) function of each list was fit before P-I curve slope and recognition threshold were calculated. Results: Equivalence evaluation results indicated good psychophysical equivalence between the 10 lists except for list 2. List 9 has a reused item. After the elimination of lists 2 and 9, multivariate ANOVA revealed a good equivalence between the remaining eight lists (p = 0.136). The mean threshold of eight equivalent lists was 10.32 ± 0.38 dB HL, while the mean slope was 5.00 ± 0.29%/dB.

NRT test in auditory neuropathy patients with cochlear implants

Abstract Conclusion: In patients with auditory neuropathy (AN), waveforms of neural response telemetry (NRT) could be present, showing characteristics of low incidence, low differentiation, and large variation. Objective: To study the characteristics of NRT in AN patients who had received cochlear implants (CIs). Methods: NRT data for seven AN patients who had received Nucleus CIs were retrospectively analyzed. Twenty-one CI implantees with sensorineural hearing loss (SNHL) were included as the control group. The incidence of electrically evoked compound action potentials (ECAPs), threshold of wave N1, and amplitude of N1-P2 in the AN group were analyzed and compared between groups. Results: The intraoperative incidence of valid ECAPs in the AN group was 42.9%, and the postoperative incidence was 66.7%, both of which were lower than those in the SNHL group, which were 95.2% and 100%, respectively. NRT in the AN group showed larger variation and lower differentiation than in the SNHL group. Wilcoxon’s non-parametric test results indicated no significant difference between AN and SNHL groups in either the threshold of ECAP or N1-P2 amplitude.

Development of a Mandarin monosyllable test material with homogenous items (I): Homogeneity selection

Abstract Conclusion. A homogeneity selection could establish a homogenous resource for Chinese Mandarin monosyllabic test lists. Objective: This study aimed to develop a set of succinct and phonemically balanced monosyllabic Mandarin recognition test lists with good item homogeneity, in an effort to meet the need for Chinese Mandarin speech recognition test materials. Methods: In reference to the Chinese phonemes distribution probability, we developed the Phoneme Allocation Table, which decided the occurrence of all consonants, vowels, and semantic tones in each list. A total of 489 monosyllables were selected and organized into 30 lists, with 25 monosyllables in each. A two-factor design was used to screen homogenous items out. Sixty normal-hearing native Mandarin speakers participated in experiment. The performance-intensity (P-I) function curve of each test item was fit by logistic regression. Items were screened out as homogenous ones using the following criteria: 1) regression R value was not <0.9; 2) slope was between 2%/dB and 12%/dB; 3) threshold was between –8 dB HL and 10 dB HL. Results: The Phoneme Allocation Table was established as a framework of 30 lists, providing a basis on which phonemically balanced monosyllabic lists can be developed. In all, 342 monosyllables with good homogeneity were screened out and can be reorganized to establish monosyllabic test lists with good sensitivity.

Successful cochlear implantation in a patient with MNGIE syndrome

Abstract A 28-year-old woman with mitochondrial neurogastrointestinal encephalomyopathy (MNGIE syndrome) undergoing evaluation for multichannel cochlear implantation is described. The case history, diagnosis of mitochondrial disease, and assessment of the benefits of cochlear implantation are documented. The hearing level with cochlear implant and speech recognition were improved significantly for this patient. MNGIE syndrome is a rare congenital disorder of mitochondrial DNA (mt-DNA). It is crucial for the otolaryngologist to have awareness of MNGIE syndrome and other mitochondrial encephalomyopathies when patients present with sensorineural hearing loss (SNHL). Cochlear implantation can be recommended to patients with MNGIE syndrome and satisfactory results can be achieved.

Determination of benefits of cochlear implantation in children with auditory neuropathy.

Background Auditory neuropathy (AN) is a recently recognized hearing disorder characterized by intact outer hair cell function, disrupted auditory nerve synchronization and poor speech perception and recognition. Cochlear implants (CIs) are currently the most promising intervention for improving hearing and speech in individuals with AN. Although previous studies have shown optimistic results, there was large variability concerning benefits of CIs among individuals with AN. The data indicate that different criteria are needed to evaluate the benefit of CIs in these children compared to those with sensorineural hearing loss. We hypothesized that a hierarchic assessment would be more appropriate to evaluate the benefits of cochlear implantation in AN individuals. Methods Eight prelingual children with AN who received unilateral CIs were included in this study. Hearing sensitivity and speech recognition were evaluated pre- and postoperatively within each subject. The efficacy of cochlear implantation was assessed using a stepwise hierarchic evaluation for achieving: (1) effective audibility, (2) improved speech recognition, (3) effective speech, and (4) effective communication. Results The postoperative hearing and speech performance varied among the subjects. According to the hierarchic assessment, all eight subjects approached the primary level of effective audibility, with an average implanted hearing threshold of 43.8 ± 10.2 dB HL. Five subjects (62.5%) attained the level of improved speech recognition, one (12.5%) reached the level of effective speech, and none of the subjects (0.0%) achieved effective communication. Conclusion CIs benefit prelingual children with AN to varying extents. A hierarchic evaluation provides a more suitable method to determine the benefits that AN individuals will likely receive from cochlear implantation.

The SP-AP compound wave in patients with auditory neuropathy.

Conclusions. This study suggests that the asynchronization of the cochlear afferent pathway may be one mechanism of the etiopathogenesis of auditory neuropathy. Objective. To investigate the characteristics of the SP-AP compound wave and its generating mechanism in patients with auditory neuropathy. Subjects and methods. The electrocochleogram (ECochG) was recorded with external ear canal electrode in patients with auditory neuropathy and normal subjects. The peak-latency, amplitude, and time course of the SP-AP compound wave were measured by using an ‘assessor-blind’ study. The discrepancy between the two groups was evaluated by statistical analysis. Results. The SP-AP compound waveform in the auditory neuropathy patient group was unrepresentative. The transient character of the SP-AP compound wave was more atypical than that for the normal cases. SP dominance (−SP/AP>0.4) appeared. The amplitude of both AP and SP was lower than that of the control group. The width of the SP-AP compound wave at one-third of its peak was greater than that of the control group.

Hearing loss in the aged: Status and interventions in China

Abstract Hearing loss is now one of the chronic diseases with the most impact on quality of life of aged Chinese people. According to the second China National Sample Survey on Disability there are 15,400,000 people over 60 years of age suffering from a hearing disorder. Among these, 2,788,600 have more than a severe hearing loss. The main causes of hearing loss in Chinese elderly people are presbycusis, long-term exposure to noise, otitis media and systematic diseases. Hearing thresholds increase approximately 10dB per decade for subjects aged 60 years and above, and remain stable from 50 to 70 years of age. A dramatic increase occurs after 70 years of age. Speech recognition showed a poor correlation with pure tone thresholds in patients older than 80 years, suggesting that the age factor should be taken into account when considering hearing amplification. The auditory brainstem response (ABR) and mismatch negativity (MMN) response have demonstrated both peripheral and central deterioration of hearing pathways in elderly people. Use of a hearing aid is the main approach for helping elderly people overcome difficulties in communication. In the past 10 years, digital hearing aids have gradually replaced analogue ones in China and have been shown to have a better effect. However, compared with the proportion of aged people with hearing loss in China, the number of those who use hearing aids is very small. This may be related to the following factors: 1) a traditional attitude towards hearing loss in the elderly; 2) financial reasons; 3) some worries due to the unfamiliarity of hearing aids; and 4) inability to manipulate hearing aids. The main complaints in elderly hearing aid users include self-hearing being too loud, a muffled feeling, excessive gain in the higher frequencies and poor speech recognition. Cochlear implants have also been used in pre-elderly and elderly patients in China. At present there is a long way to go in developing hearing healthcare services for elderly people in China. It is necessary to provide more hearing training and rehabilitation for elderly people with hearing loss using various means.

Interaction of tinnitus suppression and hearing ability after cochlear implantation

Abstract Objectives: To study the postoperative impact of cochlear implants (CIs) on tinnitus, as well as the impact of tinnitus on speech recognition with CI switched on. Methods: Fifty-two postlingual deafened CI recipients (21 males and 31 females) were assessed using an established Tinnitus Characteristics Questionnaire and Tinnitus Handicap Inventory (THI) before and after cochlear implantation. The tinnitus loudness was investigated when CI was switched on and off in CI recipients with persistent tinnitus. The relation between tinnitus loudness and recipients’ satisfaction of cochlear implantation was analyzed by the visual analogue scale (VAS) score. Results: With CI ‘OFF’, 42 CI recipients experienced tinnitus postimplant ipsilaterally and 44 contralaterally. Tinnitus was totally suppressed ipsilateral to the CI with CI ‘ON’ in 42.9%, partially suppressed in 42.9%, unchanged in 11.9% and aggravated in 2.4%. Tinnitus was totally suppressed contralaterally with CI ‘ON’ in 31.8% of CI recipients, partially suppressed in 47.7%, unchanged in 20.5%. Pearson correlation analysis showed that tinnitus loudness and the results of cochlear implant patients satisfaction was negatively correlated (r = .674, p < .001). Conclusion: The study suggests six-month CI activation can be effective for suppressing tinnitus. The tinnitus loudness may affect patients’ satisfaction with the use of CI.