Predictive value of hearing assessment by the auditory brainstem response following universal newborn hearing screening.

OBJECTIVE: This study set out to determine the accuracy with which tone pip ABR and click ABR, carried out in babies referred from universal newborn hearing screening, is able to predict the hearing outcome as determined by follow-up hearing tests. STUDY SAMPLE: The cohort of babies studied were all babies referred for hearing assessment from the universal newborn hearing screen in Sheffield, UK for the period January 2002 to September 2007, who were found to have a significant hearing impairment. DESIGN: The results of hearing assessment following referral from the newborn hearing screen were collected together with those of follow-up tests carried out up to an age when behavioural testing had established ear- and frequency-specific thresholds at 0.5, 1, 2 and 4 kHz. RESULTS: The standard deviation of the difference between the follow up and the tone pip ABR thresholds was 10.5 dB for the 4-kHz tone pip, 16.8 dB for the 1-kHz tone pip, and ranged between 21.7 and 24.7 dB for click ABR. CONCLUSIONS: The results of the study show that tone pip ABR following referral from newborn hearing screening has a similar accuracy to that reported in older subjects, and is a much better predictor compared to click ABR.

Spontaneous otoacoustic emissions measured using an open ear-canal recording technique.

Spontaneous otoacoustic emissions (SOAEs) and synchronized spontaneous otoacoustic emissions (SSOAEs) were recorded using both the standard closed-canal method of recording and a novel open-canal method which involved suspending the probe at the entrance to the ear canal with no occluding tip. In both conditions, a probe tube microphone was inserted down the ear canal to measure the acoustic pressure near the tympanic membrane. Open- and closed-canal recordings were obtained in twelve otologically normal ears, all of which exhibited SSOAEs, and 6 of which exhibited SOAEs. The results were analysed to identify any differences in response to frequency and amplitude. The different recording conditions appeared to have no significant effect on SOAE or SSOAE frequency, suggesting little effect on the SOAE generator within the cochlea. Below about 2 kHz, the amplitude for both types of emission was less for the open-canal recording when compared to the closed-canal recordings. Above 2 kHz, SSOAE amplitudes were greater in the open- than the closed-canal condition. Model stimulations of the ear canal and middle-ear acoustics are presented which were in qualitative agreement with the results shown for the effects on emission amplitudes.