Background and Aim: A common complaint of children with learning disability (LD) is difficulty in understanding speech in the presence of background noise. Evidence from animal and human studies has indicated that the medial olivocochlear bundle (MOCB) play a role in hearing in the presence of noise. The MOCB function can be evaluated by the suppression effect of the click evoked otoacoustic emission (CEOAEs) in response to contralateral white noise. The present study was conducted to compare the suppression effect of CEOAEs between LD and normal students.

Materials and Method: This research is an analytic-interventional study. The study group consisted of 20 learning disabled and 20 normal male students. The suppression effect of CEOAEs was evaluated by a comparison between CEOAEs levels in two conditions- with and without presentation of contralateral white noise.

Results: In the absence of noise there was no significant difference between CEOAEs amplitudes of two groups while there was significant difference between CEOAEs of two groups in the presence of noise. The suppression effect of CEOAEs in normal students had significant difference with LD students.

Conclusion: The reduced suppression effect in LD students indicates the reduced activity of the MOCB function and efferent pathway in LD students which affect their ability to hear in the presence of background noise. Consequently, the suppression effect of CEOAEs can be used in the test battery approach of LD children.

Background and Aim: Cervical vestibular-evoked myogenic potential (cVEMP) is one of the diagnostic tests used in assessing vestibular function. Two aims of this study were to investigate implications of cervical vestibular evoked myogenic potential in children with spastic cerebral palsy (7-12 years), and to compare vestibular function in these children and normal children.

Methods: In this cross-sectional study, myogenic potential was recorded in 31 children with spastic cerebral palsy (8 girls, 23 boys,7-12 years of age, with mean age of 8.77 years old and standard deviation of 1.52 years) and 31 normal children (13 girls, 18 boys with mean age of 8.77 years and standard deviation of 1.52 years). Cervical vestibular evoked myogenic potential was recorded with 500 Hz tone burst. The recorded parameters included p13 and n23 latency, p13-n23 pick to pick amplitude, and threshold.

Results: Myogenic Potential was recorded in 31 normal children. They had bilateral responses. In children with cerebral palsy, 21 children showed bilateral responses, 3 children had only right-sided responses, 8 children had only left-sided responses, and two children did not show any responses. The statistical significant differences were shown between the two groups in n23, p13-n23 pick to pick amplitude, and threshold (p<0.05).

Conclusion: These findings showed that cervical vestibular evoked myogenic potential can be used in children with cerebral palsy. There were significant differences in myogenic potential parameters between the two groups. More studies are needed to investigate the causes of these differences.

Background and Aim: Auditory lateralization is a binaural phenomenon that is the result of processing of interaural time and intensity cues in the central auditory system. The main advantage of this phenomenon in human is understanding speech in noisy environments due to the auditory sciene analysis and cocktail party effects . The aim of the present study was to assess the auditory lateralization ability in normal children.

Methods: Participants were 80 normal school age children (8-11 years) of both genders, 42 girls and 38 boys. Lateralization functions were determined by interaural time difference (ITD) ranging from -880 to +880 µs and interaural intensity difference (IID) ranging from -10 to +10 dB for high-pass and low-pass noise.

Results: Interaural intensity difference lateralization functions were linear , while the interaural time difference lateralization functions were S-shaped with a clear linear component from -220 to +220 µs and with an asymptote from -440 to -880 µs and +440 to +880 µs. Generally, interaural intensity difference errors were significantly less than interaural time difference tasks (p<0.0001). Age effect was only present in interaural time difference tasks (p=0.001).

Conclusion: According to these results, children with the age of 11 years performed better in lateralization using interaural time difference cues compared to other children whereas there was no difference in performance in all ages when using interaural intensity difference cues.