بررسي پديده هاي صوتي پيش عصبي )OAES( در حلزون شنوايي كودكان هنجار

A Survey of Otoacoustic Emissions (Preneural Phenomenon of Auditory Children with Normal

Introduction: Otoacoustic emissions (OAEs) or preneural phenomenon of auditory system in normal cochlea are sounds that originate in the cochlea and spread through the middle ear and into the ear canal, where they can be measured by using a sensitive microphone. OAEs are sounds generated within the normal cochlea, either spontaneously or in response to acoustic stimulation. Driscoll et al. (2000) studied a total of 940 subjects (1880 ears), with a mean age of 6.2 years old. Results indicated significant sex and ear asymmetry effects on responses that were recorded in OAEs test. Prior to this study, Nozza et al. (1997) had suggested similar findings. Also, according to Morlet et al. (1995), Kalfa et al. (1997), Aidan et al. (1997), the amplitudes of emissions are often more robust in the right ear than the left one.The present study aimed at describing the range of OAEs (Spontaneous & Evoked Otoacoustic Emissions) values obtained from children. Being handicap and ear effect has also been investigated. Material and Methods: This analytical study was administered at the faculty of Tehran University of Medical Sciences. In this study, 100 boys between 7 to 11 years old (with a mean age of 9.1) were selected. All ears had middle ear pressure between -100 to +25 dapa, normal contra lateral acoustic reflexes and bilateral pure tone threshold<20 db HL at octave levels from 250 to 8000HZ. After otoscopy and pure tone audiometry, tympanometry was performed. Provided that normal results were obtained, OAEs test could be performed in a silent environment. Results: Regarding spontaneous OAES (SOAEs), 31 percent of subjects hid spontaneous otoacoustic emissions. There were no significant differences (p>0.05) between mean amplitudes and mean frequency of emissions of the right and left ears. Similarly, in (DPOAEs) with different frequencies, no significant difference (p>0.05) was detected between mean amplitude of the right and the left ears. However, in (TEOAEs), the amplitudes of emissions in the right ear were more robust (p>0.05). Conclusion: The results of this study were quantitatively in accordance with the previous studies considering the otoacaustic emissions in children.