Intrasubject test‐retest variability in clinical electrocochleography

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Abstract
Seventeen healthy volunteers without a history of auditory or vestibular difficulty and with normal screening audiometry had bilateral (34 ears) electrocochleography performed repeatedly at 1‐week intervals. Each subject had from four to seven electrocochleograms performed on each ear. Measurements were made in the external auditory canal using a gold‐foil “TIPtrode.” Amplitude and latency for the summating potential (SP) and action potential (AP) were measured and SP/AP ratios were calculated. Averages and standard deviations for amplitude, latency, and SP/AP ratios were computed. The average SP/AP ratio was 0.22 with a standard deviation of 0.06. The range was 0.04 to 0.50. The average difference between the highest and lowest SP/AP ratio for a given individual was 0.155 (i.e., the range 0.03 to 0.31) with a standard deviation of 0.07. These normative data are useful in assessing the results of dehydration electrocochleography and in establishing how much test‐retest variation is required to suggest pathology.