Within the limits related to the effects of primary frequency and audiometric criterion, it appears that DPOAE measurements can be used to accurately identify auditory status. An approach is described, using the present data set, that allows one to assign to any measured DPOAE value (DPOAE amplitudes, DPOAE/noise) the probability that the response is coming either from the distribution of normal or impaired responses. In addition, DPOAE/noise systematically decreases as hearing loss increases over the range of hearing losses from 0 to about 40 to 60 dB HL (depending on frequency), thus potentially enabling one to differentiate hearing losses over this range. For hearing losses greater than 50 to 60 dB HL, ears do not produce measurable DPOAEs and thus, no predictive relationship exists.

Objective Universal newborn hearing screening (UNHS) test outcomes can be influenced by conditions affecting the sound-conduction pathway including ear-canal and/or middle-ear function. The purpose of this study was to evaluate the test performance of wideband (WB) acoustic transfer functions (ATFs) and 1-kHz tympanometry in terms of their ability to predict the status of the sound-conduction pathway for ears that passed or were referred in a UNHS program. Design A distortion-product otoacoustic emission (DPOAE) test was used to determine the UNHS status of 455 infant ears (375 passed and 80 referred). WB and 1-kHz tests were performed immediately following the infant s first DPOAE test (Day 1). Of the 80 infants referred on Day 1, 67 infants were evaluated again following a second UNHS DPOAE test the next day (Day 2). WB data were acquired under ambient and tympanometric (pressurized) ear-canal conditions. Clinical decision theory analysis was used to assess the test performance of WB and 1-kHz tests in terms of their ability to classify ears that passed or referred, using DPOAE UNHS test outcomes as the “gold standard”. Specifically, for 1-kHz tympanometry, performance was assessed using previously published measurement criteria and for WB measurements, performance was assessed using a maximum-likelihood procedure. Results For measurements from Day 1, the highest area under the receiver operating characteristic (AROC) curve was 0.87 for an ambient WB test predictor. The highest AROC among several variables derived from 1-kHz tympanometry was 0.75. In general, ears that passed the DPOAE UNHS test had higher energy absorbance compared to those that referred, indicating that infants who passed the DPOAE UNHS had a more acoustically efficient conductive pathway. Conclusions Results showed that: 1) WB tests had better performance in classifying UNHS DPOAE outcomes than 1-kHz tympanometry, 2) WB tests provide data to suggest that many UNHS referrals are a consequence of transient conditions affecting the sound-conduction pathway, 3) WB data reveal changes in sound conduction during the first 2 days of life, and 4) WB measurements used in the present study are objective and quick, making these tests feasible for potential use in conjunction with UNHS programs.

Newborns with confirmed hearing loss should have Cx26 testing. Cx26 testing will help define a group in which approximately 60% will have profound or severe-profound hearing loss and require aggressive language intervention (many of these patients will be candidates for cochlear implants).

Distortion product otoacoustic emissions (DPOAE) were measured in normal-hearing and hearing-impaired human subjects. Analyses based on decision theory were used to evaluate DPOAE test performance. Specifically, relative operating characteristic (ROC) curves were constructed and the areas under these curves were used to estimate the extent to which normal and impaired ears could be correctly identified by these measures. DPOAE amplitude and DPOAE/noise measurements were able to distinguish between normal and impaired subjects at 4000, 8000, and, to a lesser extent, at 2000 Hz. The ability of these measures to distinguish between groups decreased, however, as frequency and audiometric criterion used to separate normal and hearing-impaired ears decreased. At 500 Hz, performance was no better than chance, regardless of the audiometric criterion for normal hearing. Cumulative distributions of misses (hearing-impaired ears incorrectly identified as normal hearing) and false alarms (normal-hearing ears identified as hearing impaired) were constructed and used to evaluate test performance for a range of hit rates (i.e., the percentage of correctly identified hearing-impaired ears). Depending on the desired hit rate, criterion values of -5 to -12 dB SPL for DPOAE amplitudes and 8 to 15 dB for DPOAE/noise accurately distinguished normal-hearing ears from those with thresholds greater than 20 dB HL for the two frequencies at which performance was best (4000 and 8000 Hz). It would appear that DPOAE measurements can be used to accurately identify the presence of high-frequency hearing loss, but are not accurate predictors of hearing status at lower frequencies, at least for the conditions of the present measurements.

A comparison of the latency of auditory brain-stem responses (ABR) and evoked otoacoustic emissions (EOAE) has led to an interpretation for the travel of transients in the peripheral auditory system that is consistent with both sets of data. The "cochlear echo" theory for the origin of the EOAE indicates that the latency of a particular frequency component back to the ear canal should be twice the forward latency of its characteristic place in the cochlea. The latency of wave V of the ABR to tone-burst stimuli can be described as the sum of two components: (1) a component that varies with intensity and frequency in an orderly and predictable manner and (2) a component that is independent of both intensity and frequency. Because the EOAE data can be predicted by taking twice the value of component (1) of the ABR latency, this component is interpreted to be due to mechanical travel through the cochlea. A consequence of this interpretation is that the remaining neural component of the ABR latency must be relatively independent of frequency and intensity.