New dedicated instruments were installed in FY 93 to measure cochlear emissions and multifrequency immittance; upgraded software is measuring input/output function using distortion product otoacoustic emissions. Normative data for gender and age groups were developed on this equipment. Normative data for brainstem auditory evoked potentials is almost complete except for infants and children under two years of age and males over 50 years of age. Circumaural and insert phones are used to deliver the auditory stimuli for data collection. Data points for evoked potentials include absolute and interpeak latencies, and amplitude ratio of waves I and V collected under permutations of stimulus parameters. Results are comparable others using similar instrumentation and study variables. Important data sets in otoacoustic emissions have been completed from the study of cochlea emissions. For example, test-retest reliability is excellent though 2000Hz for transient otoacoustic emissions (TOAE's) and though 3000Hz for distortion product otoacoustic emissions (DPOAE' s) on healthy subjects with normal hearing using the same instrument. For comparison, data has been collected, but not yet analyzed, on the second instrument. To develop a normative data base for healthy subjects with normal hearing a study of TOAE' s comparing the repeatability of measures of spontaneous emissions across techniques and instrumentation is being conducted with two instruments and two test paradigms. Data are being collected on growth function (input/output function) looking at linearity for 1000, 2000, 3000, 4000 and 6000Hz in normal subject. These data may be important when comparing pathologic conditions for which growth function is thought to be non-linear. Data collection of multi-frequency immittance is complete on one set of normal subjects but analysis of the data for ear canal volume and resonance peak will be completed later. Under a planned amendment to this protocol normative vestibular values will be developed for the newly installed rotational chair. Carefully drawn norms are essential to the work of the CAU because of the complex patient populations.
