Abstract
Acoustic reflex thresholds (ART) were measured ipsilaterally in 20 neonates, 220 children with normal hearing and 56 children with sensorineural hearing loss, using a probe-tone frequency of 660 Hz. Middle-ear function was assessed with tympanometry (220 Hz probe tone) in all children. All the neonates had normal tympanograms and middle-ear pressure better than — 1 kPa, even a few hours after birth. The mean acoustic reflex threshold (ART) averaged over the frequency range 0.5–4 kHz was 85 dB HL, with standard deviations (SD) varying between 5 and 9 dB. With broad-band noise (BBN), the mean ART average was 57 dB HL with SD ± 10 dB. Measurements of the ART on the children with normal-hearing and at an age of 1 month up to 5 years showed that the ARTs increased in relation to age. At 4 kHz the ARTs increased from an age of 2 months. At an age of one year 28% of 40 ears failed to manifest a reflex at the maximum testing level (90 dB HL). At frequencies 1.0 and 2.0 kHz the mean ART increased from 85 dB HL in neonates to 90 and 92 dB HL at an age of 5 years. The standard deviations in the different age groups varied between 4 and 9 dB for pure tones and 6–8 dB for BBN. Twenty (9%) of the 220 children with normal hearing had elevated ARTs by puretone stimuli and 19 by BBN. No reflexes could be elicited at 0.5 kHz and at 1.0 and 2.0 kHz the ARTs were abnormally elevated. Fifty-six children (104 ears) had a sensorineural hearing loss varying between 20 and 75 dB HL. The ARTs for pure tones were found to be in the normal range in 47%. The reflex threshold was elevated in 53%. The corresponding values using BBN were 64% and 36%. The sensitivity of the ART in correctly identifying all subjects with sensorineural loss was 58% for tones and 66% for BBN. There is a considerable risk that children with impaired hearing and with normal ART can be identified as having normal hearing. The specificity of ART in identifying all normal-hearing children as normal was good or 89% for tones and 86% for BBN. The acoustic reflex should be used with great caution for the prediction of hearing level in the young pediatric population.