Introduction: Otoacoustic emissions are low density sounds produced from intact cochlea measureable in the presence of an intact conduction structure. The goal of this study was to assess the surgical success rate after stapes surgery by standard audiometric tests, Distortion Product Otoacoustic Emission (DPOAE) and Transient Evoked Otoacoustic Emission ((TEOAE)) as methods of evaluation of postoperative hearing. Methods: A descriptive-analytic study was conducted on 50 patients with otosclerosis at Yazd Shaheed Sadoughi Medical University from March 2004 till October 2007. (TEOAE), DPOAE and other behavioral audiometric tests were performed before, three months and six months after surgery on patients and results were compared. Results: The air-bone gap threshold decreased significantly in audiogram of patients after surgery. Prior to surgery, (TEOAE) and DPOAE responses were not recordable in any of the patients, but after surgery, they were recordable in only two patients. Conclusion: Although conductive hearing loss improved significantly in patients who underwent successful stapes surgery, OAE tests were recordable in an insignificant number of patients. Therefore, this is not an optimal method for evaluating the surgical success rate.

Objective: Survey and comparison between the physical characteristics of Distortion - Product Otoacoustic Emissions of 1- 59 day-old normal-hearing newborns referred to TUMS, Rehabilitation School, Audiology department, 2002Method & Material: This analytical-descriptive study was conducted on the ears of 102 easy method selected newborns. The tests included: otoscopy, BOA, Immittance audiometry, DPOAEs, and ABR if necessary. The amplitude and frequency of 2f1-f2 emissions of DPOAEs evoked by two pure tones (L1=65 dBSPL, L2=50 dBSPL and f2/f1=1.2) were also calculated.Results: 1- All normal hearing newborns have normal DPOAEs. No significant difference was observed in test-retest.2- The amplitude of the DPOAEs to the right ear is significantly greater than the amplitude of the left ear (P<00.05).3- No significant difference was observed between newborn's DPOAEs in terms of their gender.Conclusion: DPOAEs could be measured quickly and noninvasively and are excellent tools for the screening of newborn hearing loss. The results are valid only within the Context of this research.

Objective: To determine SOAE, (TEOAE), and DPOAE, characteristics in normal-hearing school boys.Method and Material: This cross-sectional study was conducted on 7-11 year-old normal - hearing boys (n = 100) living in 12th zone of Tehran. OAEs also performed and investigated if otoscopy, pure tone and imrnittance audiometry were normal.Both handedness and ear effects was also considered.Results: 31% had SOAEs. No significant difference between the right and left ear SOAEs frequency and amplitude means.1, 3 kHz and total response (TEOAE)s amplitude was significantly different between two ears. There was no significant difference between both ear DPOAEs amplitudes, whereas the left - handed boys' DPOAE amplitude is greater than the right - handed ones' amplitudes.Conclusion: As some results including equal SOAEs of both ears, no difference between both ears SPOAEs amplitude, and handedness effect on the amplitude do not agree with other studies, these finding should be considered in testing OAEs of school boys.

BACKGROUND AND OBJECTIVE: Noise-induced hearing loss remains as the most common problem in industrial societies. This research was conducted to study noise-induced hearing loss by distortion-product otoacoustic emissions (DPOAEs).METHODS: This study was carried out on 12 male New Zealand White rabbits including control (exposed to noise) and experimental (exposed to 95 dBA SPL white noise at 500-8000 Hz for 8 hours per day during 5 consecutive days). DPOAEs were measured and compared in days zero (before exposure as baseline), eighth (experimental: an hour after latest exposure to noise for Temporary Threshold Shifts: TTS), tenth (experimental: 48 hours after latest exposure to noise for Permanent Threshold Shifts: PTSs).FINDINGS: The most and the least values of TTSs, PTSs and DPOAEs amplitude in noise group were correspond to frequencies of 5888.50 Hz and 588.00 Hz, respectively (p<0.05). There was a significant difference between TTSs, PTSs and DPOAEs amplitude at different frequencies in right and left ear of noise group (p<0.05). This difference was related to frequency 5888.5 Hz in each of right and left ear of noise group compared to other frequencies in same ear (p<0.05). There were not any significant difference between TTSs, PTSs and DPOAEs amplitude of right and left ear of noise group at different frequencies (p>0.05).CONCLUSION: Excessive noise can cause TTSs and noise-induced PTSs and decreased DPOAEs amplitudes. Therefore, DPOAEs can be attributed as a useful tool for study of noise-induced hearing loss.

Objective: Acoustic stimulation of auditory efferent system causes contralateral shift in the OAEs amplitude. In this study the contralateral suppression effect of pure tone & NBN at center frequencies of 1, 2 & 4 kHz Frequencies has been evaluated in the right ears of normal 19 to 27 years old adults. Materials & Methods: The data were elicited from 37 subjects (15 males & 22 females) with normal hearing who participated in this study. After determining the level of NBN by loudness adjustment between pure tone at 70 dBHL at 1, 2 & 4 kHz in left ear, EOAEs was measured using tone burst at central frequencies of 1,2 & 4 kHz in right ear. Then the amplitude shift of TBEOAEs was evaluated at the presence of contralateral pure tone & NBN stimuli. Results: There was a significant shift in the amplitude of TBEOAEs by contralateral stimulation of pure tone & NBN which was greater in NBN. The magnitude of amplitude shift was become greater at high frequencies of contralateral stimuli. Conclusion: There was a decrease in the amplitude of TBEOAEs by contralateral stimulation and the stimulus with greater frequency band had greater effects on contralateral suppression. The impact of this effect was highly depend on the spectrum & frequency of contralateral stimuli.

Objective: Evaluation of cochlear function in neonates and children suffering from meningitis according to EOAE results.Matherials & Methods: In this study 40 children and neonates suffering from meningitis ranging from one day to 12 years old were evaluated with EOAE (DP-OAE & TE- OAE) during 7 to 14 day after discharge from hospitalResults: From our 40 patients, normal cochlear function was observed in 35, bilateral abnormal cochlear function in 4 and unilateral abnormal cochlear function in 1. In these 5 cases (12.5% of our patients), detected by EOAE tests, sensorineural hearing loss was seen. This result was confirmed by ABR test in hospital.Conclusion: Abnormal cochlear function and sensorineural hearing loss as a complication of meningitis (if present) can be detected in early stages by the EOAE tests.