The purpose of this study is to evaluate whether steady-state evoked potential (SSEP) can be used for objective estimation of auditory thresholds in patients with noise-induced hearing loss (NIHL). Eleven subjects (22 ears) with a characteristic audiometric notch between 3000 and 6000 Hz participated in this study. Both pure-tone thresholds and SSEP thresholds were obtained for each ear of all subjects. The correlation of SSEP thresholds and pure-tone thresholds was assessed. The results show that SSEP thresholds predicted pure-tone thresholds with correlation coefficients (r) of 0.86, 0.92, 0.94 and 0.95 at 500, 1000, 2000 and 4000 Hz respectively. Typically, the SSEP thresholds overestimate the pure-tone thresholds by 10-20 dB, but they closely reflect the configuration of the audiogram. The strength of the relationship between SSEP and pure-tone thresholds increased with increasing frequency and increasing degree of hearing loss. In conclusion, SSEP can be used as a reliable and objective tool to assess auditory thresholds in patients with noise-induced hearing loss with high-frequency dips.

We evaluated the long-term development of categorical auditory performance and speech intelligibility rating of Mandarin-speaking prelingually deaf children within 5 years after early cochlear implantation. The categorical auditory performance increased after cochlear implantation, the median categorical auditory performance after 1 year of implantation was 4 and became 7 three years after implantation. The median categorical auditory performance remained to be 7 till 5 years after implantation. There was significant difference in categorical auditory performance category between 'before implantation' and '1 year after implantation', also between '1 year after implantation' and '3 years after implantation'. But no significant difference was found between 3 years and 5 years after implantation. The median speech intelligibility rating before implantation was 1. After 2 years of implantation, the median speech intelligibility rating became 4. Significant difference was found between these two time points. Three years after implantation, the median speech intelligibility rating improved to 5 and maintained at that level till 5 years after implantation. Eighty-one per cent (17/21) of our subjects reached the maximal category (7) of categorical auditory performance 5 years after implantation. Eighty-one percent (17/21) of our subjects achieved the highest category (5) of speech intelligibility rating 5 years after implantation.

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