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Introduction: It is well recognized that hearing is critical to speech and language development, communication, and learning. Otoacoustic emission (OAE) is an efficient and sensitive method to identify subjects at risk for auditory impairment. Infants who require admission to neonatal intensive care unit are reported to be at 10-20 times greater risk for hearing impairment. The porpuse of this study was to investigate the incidence of hearing impairment in neonates screened by OAE. Materials and Methods: In a cross-sectional study, 148 newborns having risk factors for hearing impairment reffering to Taleghani hospital of Arak and Aboozar hospital of Ahwaz were evaluated. All clients had normal otoscopic findings. Transient evoked (TEOAE) and distortion-product otoacoustic emissions (DPOAEs) were measured in both ears. If the results of otoacoustic emissions were not normal, these tests were repeated one month later. Patients who did not pass the second stage were reffered for comprehensive auditory evaluations. Data analysis was performed using Kolmogrov-Smirnov and t-tests. Results: 41 and 28 cases could not pass the examining test at the first TEOAE and DPOAE examination, respectively. Also, 23 and 16 cases did not pass the examining test at the second TEOAE and DPOAE evaluations, respectively. These participants underwent auditory brainstem response evaluation and 11 of them had abnormal responses. In 5 cases of confirmed ones, hearing impairment was due to aminoglycoside side effects. Conclusion: OAE hearing screening of at-risk newborns is a clinically beneficial approach to early detection of hearing impairment. Regarding the high prevalence of hearing loss in our subjects (7.43%), prevention of its complications is highly recommended in this population.

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Background: Trauma noise is one of the major physical pollutants in modern societies. Sound conditioning, on the other hand, is known as one of the mechanisms for protecting the hearing system. Materials and Methods: In this experimental study, 15 three month-old male white New Zealand rabbits were divided into three groups. The equipments used in this study included a sound generator, a loudspeaker, an exposure box, a sound level meter, and a distortion product otoacoustic emission (DPOAE) device. The rabbits were assigned to trauma noise exposure, conditioning noise exposure, and control groups. The conditioning and traumatic sound levels were respectively 80 and 105dB within the 500-3000 Hz frequency. Results: Conditioning noise at the level of 80 in combination with trauma noise enhanced the rabbits hearing system tolerance up to 13-17 dB so that in all frequencies there were significant differences between the trauma noise exposure group and the sound conditioning and trauma noise conditioning group (P<0.05). Conclusion: Sound conditioning can act as an effective factor in protecting the hearing system against trauma noise.

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Background: Otoacoustic emissions (OAEs) are faint sounds generated within the inner ear that can be regarded as a sensitive tool for reflecting inner ear status. There are various factors that may influence OAE recording. One such factor that has not been extensively examined to date is body position. The aim of this study was to examine the effect of body position on the OAE responses of adults with normal hearing. Materials and Methods: In an analytic cross-sectional study, 26 normal hearing adults (18-25 years old) were evaluated. Transient OAEs (TEOAEs) were recorded in five different positions: supine, sitting, side-lying, 30°-Up, and 30°-down to evaluate their inner ear function. Data were analyzed using SPSS software 17. Results: Mean TEOAE amplitude values were significantly higher in the side-lying position compared to other positions (P=0.01). The most significant TEOAE amplitude differences were observed at the high frequencies (3000 Hz and 4000 Hz) in side-lying position orientation compared to low and medium frequencies. Conclusion: The results from the present study revealed that body position has a remarkable effect on inner ear function, and this effect is more obvious at high frequencies.