To study the basic properties of DPOAE including the Spectral History of DPOAE in subjects with normal hearing, Thresholds of octave pure tone from 0.125 to 8 kHz and Tympanometry in 226 Hz were measured to exclude the abnormal function of middle ear in 38 ears of 19 young subjects, then the spectrum of DPOAE、DP - Gram、I/O function curve、Latency and Spectral History of DPOAE were recorded. DPOAE can be detected in all subjects, the amplitude of DPOAE has great intersubjectal variety, the largest two values are 9.11 dB SPL at 1. 5 kHz and 7.72 dB SPL at 6 kHz, DP - Gram has two peaks. The amplitude increased with the increasement of primary tone level, The latency shortened with the increasement of primary frequency. The Spectral History in most of them is flat, the coefficiency of variance is 2. 53?1. 89% , the abnormal rate is 18.5% implying the Spectral History maybe have role in predicating subclinic cochlear lesion.

Objective To investigate the appropri ate changes of the central masking effect(CME) when there were pathologies in d ifferent segment of auditory pathway,so as to give some instructions in cli nical masking test. Methods We tested the subjects with one ear normal and th e other ear diseased. The diseased ears included conductive deafness in 30 ca ses?sensory deafness in 27 cases and retrocochlear deafness in 7 cases. Results The pure conductive deafness had very little effect on CME; secretory otistis media and chronic suppurative otistis medi a made CME lower than normal due to the secondary cochlear impairment .When su dden deafness companied with vertigo,CME appeared much higher than the normal and appeared great difference individually;but CME appeared lower than normal at other kinds of cochlear deafness ears.CME appeared differently at retrocochlear deafness ears. Conclusion Audiometry results should be corrected when th e masker higher than 40 dB EM,because the masker can make the CME higher than 5 dB in the conductive impairment ears.In the sudden de afness companied with vertigo ears,CMEs were too high and too individually to fi nd a suitable correction for PTT.Insert earphone should be used in measuring the air-conduction PTT,and bone-conduction PTT test might be given up.

Transient Evoked otoacoustic emissions(TEOAE) in 25 hearing- normal youngers was analysed to study its basic character and the influences of different stimulus intensities on the amplitude and the power spectrum which may be useful to identify the hearing-loss subjects as the standardline. We find that the average amplitude of TEOAE is 5.97, 9.22, 12. 76 dB SPL under three intensities,the frequencies of the spectrum distribute from 0 to 6 000 Hz. The two maximal values are located in 1 025 Hz and 1 513 Hz seper-ately. The amplitude of TEOAE increases with the stimulus tone's growth. We conclude that it's necessary to consider completely when evaluating the patient's hearing function by TEOAE's power spectrum on account of its incontinuity and decrease in high frequency.