No effect of occupational noise exposure on auditory brainstem response and speech perception in noise.

The primary aim of this study was to investigate whether auditory brainstem response (ABR) and speech perception in noise (SPiN) were associated with occupational noise exposure in normal hearing young factory workers. Forty young adults occupationally exposed to noise and 40 non-exposed young adults (control group) from Zhejiang province in China were selected. All participants presented with normal hearing thresholds and distortion product otoacoustic emissions. Participants were evaluated with the Mandarin Bamford-Kowal-Bench (BKB) test and ABR. The latter was obtained for click stimulus at 50, 60, 70, 80, and 90 dBnHL. Peak-to-trough amplitudes and latencies for waves I and V were obtained. The ABR wave I amplitude, the wave I/V amplitude ratio, the slope of the wave I amplitude growth as a function of stimulus intensity (AMP-ISlope), and the wave V latency shift with ipsilateral noise (LAT-VSlope) were used as ABR outcomes. Finally, equivalent continuous average sound pressure level normalized to 8 h (LAeq.8h) and cumulative noise exposure (CNE) were obtained for noise-exposed participants. No significant differences between groups were found for any ABR outcomes. Noise-exposed participants exhibited worse BKB scores than control group participants. A multivariate regression model showed that 23.3% of the variance in BKB scores was explained by group category (exposed vs. non-exposed) and hearing thresholds. However, since none of the ABR outcomes exploring cochlear synaptopathy were associated with noise exposure, we cannot conclude that cochlear synaptopathy was the contributing factor for the differences between groups for BKB scores. Factors that go beyond sensory processing may explain such results, especially given socio-economic differences between the noise-exposed and control groups. We conclude that in this sample of participants, occupational noise exposure was not associated with signs of cochlear synaptopathy as measured by ABR and BKB.

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

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.

[Test-retest reliability of Mandarin monosyllable lists: a multi-center study in Chinese dialectal regions].

OBJECTIVE: To develop 22 Chinese Mandarin monosyllable lists with good psychometrical equivalence. This study was to evaluate the test-retest reliability of these lists when it was used in speech recognition test in normal hearing dialectal speakers. METHODS: Seven cities including Dalian, Shanghai, Hangzhou, Wuhan, Guangzhou, Fuzhou and Xiamen were selected as testing centers which contain 6 typical Chinese dialectal regions including north of China, East of China, north of Fujian, south of Fujian, Guangdong and mid-south of China. At each center, 22 local normal hearing people were selected to join this study. Every participant was tested by each recognition test of all 22 lists twice in two sessions and same test order respectively. The second run of testing was carried out within 10 days-1 month since first run of testing. RESULTS: There was a significant correlations between scores obtained at the two sessions (r = 0.682, P < 0.01). Paired student-t test had shown that a gross score of all dialectal participants was significantly higher than that of initial test to retest (P < 0.01). The mean increment of score was (2.7 +/- 10.1)%. A significant difference of test-retest score in 7 sites was 19.8% and it was equal to 5 test items. A one way ANOVA analysis had indicated that there were statistically significant difference between the score improvement of 7 test sites (P < 0.01). Another analysis had shown that there was no significant correlation between test-retest score improvement and intra-session intervals (P = 0.947). CONCLUSIONS: Mandarin monosyllabic recognition test seems to be more stable, and the present study has indicated a systematic differences in Chinese Mandarin monosyllable recognition scores between test and retest. Monosyllable recognition test is not susceptible to memory effect. Pearson's correction analysis is not suitable to evaluation for test-retest reliability.

[Development and evaluation of standardized Mandarin monosyllable audiometric materials].

OBJECTIVE: To develop a set of Mandarin monosyllabic list for the goal to use as a standardized speech recognition assessment tool in China with sufficient validity, reliability and sensitivity. METHODS: Thirty lists were designed based on the following criteria: efficiency, phonemic-balance, familiarity and coverage, while each list was designed corresponding to 25 monosyllables. These lists were read by a male broadcaster, recorded digitally and composed into compact disc. Our work consisted of three phases. Phase I: Sixty adults with normal hearing were recruited from Beijing to repeat as many syllables which they heard as possible. According to the randomized block design, 30 lists were presented with 6 intensities including -1 dB, 5 dB, 11 dB, 15 dB, 21 dB and 27 dB HL(speech). The lists and intensities were counterbalanced across all participants. Recognition scores in individual intensities for each list were calculated, and then logistic regression was utilized to fit Performance-Intensity (P-I) function. Two-way (list No. and Intensity) repeated measurement analysis of variance and Post-Hoc Tukey HSD test indicated that 22 lists were equivalent. Phase II: Twenty-two oral/aural normal adults were recruited to assess monosyllable recognition scores with the 22 equivalent lists at 10 dB HL(Speech), according to the Latin-Square design. Tests were administered twice for all participants with the same procedure and situation during 6 to 35 day intervals. The differences in scores (after a "rationalized" arcsine transformation) among 22 lists across over the two sessions is 9.3%, the data were collected from 22 participants, the measurement error was calculated by SD (standard deviation), the critical difference (CD) for test score improvement was 18.3% (determined as SD x 1.96, in 95% confidence level). Phase III: Eighteen participants with sensorineural hearing loss were recruited to assess recognition perception using 18 equivalent monosyllable lists at 30 dB suprathreshold based on Latin-Square design. Tests were administered twice by using the same procedure and situation within 1 to 16 day intervals. The same approach in Phase II was utilized to calculate SD (8.3%). The CD was calculated as 16.3% (in 95% confidence level). RESULTS: A set of standardized Mandarin recognition assessment material had been developed and it consisted of 22 equivalent phonemic-balanced lists with 25 monosyllables each. Approximately, every single list took 2 minutes, and thus it might be appropriate for clinical assessment. The P-I functions reveal that the recognition threshold was (8.30 +/- 0.84) dB HL(speech) and the slope of PI functions was (4.0 +/- 0.3)%/dB for adults with normal hearing. When a set of Mandarin monosyllable lists was utilized as an assessment tool, the critical difference of 18.3% (for normal-hearing adults) and 16.3% (for hearing-impaired adults) would be a key for clinicians to assess the improvement of speech recognition ability appropriately with statistically significance. CONCLUSION: In this study, a new Mandarin monosyllabic lists has been successfully developed with a sufficient validity, reliability and sensitivity for clinical evaluations, thus it might be convenience and helpful to be used as a standardized speech recognition assessment tool in China.