Ipsilateral acoustic reflexes in infants.

Ipsilateral acoustic reflex thresholds were studied in otoscopically normal ears of infants 2 weeks to 12 months old. Probe tones of 220 and 660 Hz and pure tone activators were used. Reflex recordings were free of activator artifact and were measured using quantitative standards. Reflexes were detected in 85% to 95% of infant ears for 500, 1,000, and 2,000 Hz activators but were present in only 76% of ears at 4,000 Hz. Median thresholds of 80 to 85 dB hearing level were obtained with all activators and both probe tones. There were no differences in proportions of reflexes obtained with the two probe tones. With a 500-Hz activator, thresholds at 220 Hz were lower than those at 660 Hz, while no threshold differences were demonstrated between probe tones at other activators. No relationship was demonstrated between age in the first year of life and presence or threshold of reflexes. Ipsilateral acoustic reflex measures have potential use in the identification of hearing loss and middle ear disease in infancy.