Comparison of ASSR, ABR and 40 Hz AERP Response Thresholds at Different Frequencies and Their Forensic Applications / 法医学杂志

OBJECTIVES@#To explore the relationship between the frequency characteristics and response threshold of auditory steady-state response (ASSR), auditory brainstem response (ABR) and 40 Hz auditory event related potential (40 Hz AERP), and their application values in forensic medicine.@*METHODS@#Thirty volunteers with normal hearing (60 ears) were selected to perform pure tone audiometry (PTA) threshold and ASSR, ABR and 40 Hz AERP response threshold tests in the standard sound insulation shielding room, and the results were statistically analyzed by SPSS 22.0 software.@*RESULTS@#At 0.5 kHz and 1.0 kHz frequencies, the correlation between 40 Hz AERP response threshold and PTA threshold was good, which was better than that of ASSR and ABR response threshold. At 2.0 kHz and 4.0 kHz frequencies, the correlation between ASSR and ABR response thresholds and PTA threshold was good, which was better than that of 40 Hz AERP response threshold.@*CONCLUSIONS@#To evaluate the hearing at 0.5 kHz and 1.0 kHz frequencies, it is recommended to use 40 Hz AERP and ASSR to comprehensively assess the PTA threshold of the subjects. To evaluate the hearing at 2.0 kHz and 4.0 kHz frequencies, ABR and ASSR are recommended to assess the PTA threshold of subjects comprehensively. The combination of ASSR, ABR and 40 Hz AERP can improve the accuracy of hearing function evaluation.

Application value of 40Hz auditory event related potential in hearing assessment in noise-exposed workers / 中国职业医学

OBJECTIVE: To evaluate the application value of 40 Hz auditory event related potential(40 Hz AERP) in hearing assessment in workers exposed to noise by observing the consistency between pure tone audiometry(PTA) and 40 Hz AERP. METHODS: A total of 240 ears of 120 workers who exposed to noise with PTA high-frequency hearing threshold > 25 dB were selected as the research subjects using the convenient sampling method. The thresholds of PTA and 40 Hz AERP at different frequencies were investigated. According to the average hearing threshold of PTA language frequency, the workers were divided into normal hearing group and mild-, medium-, medium-severe-, severe-hearing loss groups, and the difference and correlation between the thresholds of 40 Hz auditory potential and PTA were analyzed. RESULTS: The response thresholds of 40 Hz AERP of 0.5, 1.0, 2.0 kHz in ears of normal hearing group, and mild-and moderate-hearing loss groups were higher than the PTA hearing threshold(P<0.01), while the 40 Hz AERP response thresholds of 0.5 kHz in the ears of medium-severe-and severe-hearing loss groups were lower than the hearing thresholds of PTA(P<0.05). The different value of the response threshold of 40 Hz AERP and PTA of 1.0 and 2.0 kHz in ears of normal hearing group was higher than 0.5 kHz(median: 25.0 vs 15.0 dBHL, 30.0 vs 15.0 dBHL, P<0.01). Except for 0.5 and 1.0 kHz of mild-hearing loss group, the different value of the response threshold of 40 Hz AERP and PTA in ears of the other hearing loss groups were lower than that of the normal hearing group(P<0.01). The 40 Hz AERP response threshold was frequency-specific and correlated well with PTA at the same frequency. The correlation coefficients of 0.5, 1.0 and 2.0 kHz were 0.744, 0.732 and 0.665 respectively(P<0.01). CONCLUSION: It is feasible to evaluate PTA in noise-exposed workers using 40 Hz AERP response threshold, but the 40 Hz AERP cannot completely replace PTA. The measurement frequency and the degree of hearing loss should be considered simultaneously.

Frequency Characteristics of AEPs in Normal Young Adults and Comparison of Their Response Threshold and Pure Tone Audiometry Threshold / 法医学杂志

Objective The tests of three types of auditory evoked potentials （AEPs） were performed on normal young adults, to understand the frequency characteristics of different testing methods and the relationship between response threshold and pure tone audiometry threshold of different methods, and to discuss the forensic value of 3 types of AEPs to evaluate hearing function. Methods Twenty normal young adults were selected, their standard pure tone audiometry threshold, short-term pure tone audiometry threshold and the response threshold of 3 types of AEPs （tone burst-auditory brainstem response, 40 Hz auditory event-related potential and slow vertex response） at 0.5 kHz, 1.0 kHz, 2.0 kHz and 4.0 kHz were recorded. The relationship between the response threshold and standard pure tone audiometry threshold, short-term pure tone audiometry threshold of 3 types of AEPs at different frequencies as well as the differences between different types of AEPs were analyzed. Results The short-term pure tone audiometry threshold was higher than the standard pure tone audiometry threshold at each frequency. The response threshold and standard pure tone audiometry threshold of the 3 types of AEPs all had a certain correlation, and the response threshold of the 3 types of AEPs was higher than short-term pure tone audiometry threshold and standard pure tone audiometry threshold at each frequency. The differences in the differences between the response threshold and standard pure tone audiometry threshold of the 3 types of AEPs at different frequencies had statistical significance. Linear regression mathematical models were established to infer the standard pure tone audiometry threshold （hearing level） from response threshold （sound pressure level） of 3 types of AEPs of normal young adults. Conclusion When using response threshold of different types of AEPs to estimate pure tone audiometry threshold, conversion and correction are needed. Combined use of different types of AEPs could improve the accuracy of hearing function evaluation.

The Experimental Study on the Changes of Hearing Function and Cochlear Morphology in Rat Diffuse Brain Injury Model / 听力学及言语疾病杂志

Objective To study the changes of hearing function and cochlear morphology on diffuse brain in-jury model in rat .Methods One hundred and fifty SD rats with normal hearing were randomly divided into five groups ,each group consisted of 30 SD rats ,including a control group and four experimental groups which endured diffuse brain injury(DBI) from one to four weeks .Diffuse brain injury model of rats were established ,then ABR , 40 Hz AERP and ASSR examination ,light microscopy ,electron microscopy were used to evaluate the change of hearing function and morphology .Results The difference of ABR ,40 Hz AERP and ASSR thresholds between the experimental and the normal control group were significant (P<0 .05) .The thresholds of ABR ,40HzAERP and AS-SR were increased in the first week of DBI ,then the threshold continuously increased in the second and third week , at last the threshold decreased in the fourth week .The results under scaning electron microscope demonstrated that the ciliums of the majority of outer hair cells lodged in the first week of DBI .The results under transmission electron microscope showed that in the first week of DBI ,there were edema and denuration of mitochondrial ,mitochondrial cristaes were obscured or disappeared .The changes were deteriorate in the second and third week ,whereas the changes were mitigatal in the fourth week .Conclusion Cochlear morphology and hearing damage were observed in diffuse brain injury model of rats .