Objectives Auditory cortex in each hemisphere mostly receives the sounds from the opposite ear. The present study aimed at the contralateral dominance of auditory brainstem response (ABR) among the ears in preterm neonates by comparing sex and gestational age. Methods Transient Evoked Otoacoustic Emission (TEOAE) and Auditory Brainstem Response (ABR) were recorded at 3 months postconceptional age (PCA). The performance of two ears in ABR was compared. In addition, performance of each ear was analysed in females and males. A comparison of moderate gestational age also was performed. Twenty preterm neonates from 32 to 36 weeks gestational age admitted to the neonatal intensive care unit at Shafizadeh Children’s Hospital were participated. Results No significant asymmetry in ABR absolute latency and inter-peak intervals of right and left ears in preterm infants was noticed. Females and males did not demonstrate statistically significant values in ABR latencies. Moreover, the results of four gestational ages were not statistically different from each other. Conclusion The maturation of the auditory brainstem pathways most likely take places in both hemispheres simultaneously, independent of sex in preterm infants. Changes of gestational age in each month do not impact on the maturation of the auditory brain pathways.

Objective Congenital hearing loss is a disabling and multi-factorial disease that affects on newborn and children. This study aims to demonstrate the relationship between risk factors for hearing loss and the results of Otoacoustic emission in Iranian newborns. Methods We have retrospectively considered 536 newborns admitted to the Audiology Department of a Children’s Hospital in the north of Iran. Transient Evoked Otoacoustic Emissions (TEOAEs) was recorded during the first week of birth, and the risk factors of hearing loss were collected. Results We found that parent relatives and family history were significantly correlated with OAEs refer results. Moreover, hyper-bilirubinemia indicated a significant correlation only with first right OAEs. There was a significant correlation between gender and first left and right OAEs. Other risk factors such as seizure, transient tachypnoea of the newborn (TTN) and respiratory distress syndrome (RDS), and lip cleft had a significant correlation with first left and right OAEs results; however, these correlations were not relatively highlighted. Conclusions Generally, our data confirm that hearing screening is an absolute necessity in the greater number of newborns. People who got consanguineous marriages should be aware of high incidence of the congenital hearing loss due to parent relatives and family history.