Influence of acquisition parameters on the measurement of click evoked otoacoustic emissions in neonates in a hospital environment

There is much interest in the introduction of a universal neonatal hearing screening programme. Screening programmes using high-risk criteria have been used for some time, but 50 per cent of deaf and hearing-impaired neonates are not identified because they are not classified as high risk for hearing impairment at birth. Otoacoustic emission (OAE) measurement is widely regarded as a technique likely to be suitable for universal hearing screening. To examine this, otoacoustic emissions were measured from 351 neonate ears at a large maternity hospital. Of particular interest were the practicalities of recording OAE in a hospital environment, the establishment of an appropriate age at which screening should be performed on neonates and investigation of the relative advantages of different recording techniques. Main findings were: (I) low OAE levels relative to noise during the first 24 to 48 hours post partum; (2) lower OAE signal to noise levels in the low frequencies irrespective of age; (3) increase of overall signal to noise ratio in frequencies above 1 kHz through the use of a shortened response window; and (4) OAE recording could be performed easily in mothers' hospital rooms prior to discharge.