Publication:

Effect of age on acoustic reflex thresholds in neonates and infants with normal hearing

Background High frequency (1000 Hz) probe tone holds substantial promise for carrying out acoustic reflexes in neonates and infants. A limited number of studies indicates that acoustic reflex thresholds (ART) also change significantly with age as the newborn hearing system matures. However, there is a need for obtaining more data before using it in a clinical population. The aim was to investigate effect of age of infants on ARTs. Effect of activator signal was also explored.

Methods ARTs were monitored using a 1 kHz probe tone for the 500 Hz, 1 kHz, 2 kHz, and 4 kHz pure tone activators in neonates and infants in the age range of 6 to 8 weeks were analysed.

Results The mean ARTs for neonates were lower compared to infants. Results of repeated measure ANOVA showed that there was a statistically significant age effect. Also, ARTs for high frequency activator signals were significantly higher than the ARTs for low frequency signals.

Conclusions The acoustic reflexes can be elicited for 500, 1000, 2000, and 4000 Hz when monitored using a 1000 Hz probe tone. There is an effect of age and activator signal on the acoustic reflex threshold. The data obtained in the present study can serve as normative for 0-1-week neonates and 6-8-weeks infants.