Distortion product emissions in normal-hearing and low-frequency hearing loss carriers of genes for Waardenburg's syndrome.
Eight patients with Waardenburg's syndrome (WS) with normal hearing and 3 additional patients exhibiting a low-frequency hearing loss were tested for the level of the acoustic distortion product 2f1-f2 by means of the Otodynamics Distortion Product Analyser (ILO92). Wide notches in distortion product otoacoustic emissions (DPOAEs) between 1,000 and 3,000 Hz were found in 7 (12 ears, 87.5%) examined patients with normal audiograms, which was a significantly higher rate than that found in the control group (10%). The 3 patients with low-frequency hearing loss a gave a consistent pattern in audiometric configuration shown by both pure tone audiograms and DPOAEs. It is concluded from these initial results that DPOAEs may be a useful approach to identifying subclinical pathologic aberrations in the inner ear in WS patients, and may be a predictor of low-frequency sensorineural hearing loss.