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July 1986

The Normal Summating Potential Recorded From External Ear Canal

Author Affiliations

From the Departments of Otorhinolaryngology and Communicative Sciences and of Neurology, Baylor College of Medicine, Houston.

Arch Otolaryngol Head Neck Surg. 1986;112(7):759-768. doi:10.1001/archotol.1986.03780070071016

• With a "plastic leaf" electrode, cochlear summating potential (SP) and auditory nerve action potential (AP) responses to rectangular-pulse clicks were recorded from the ear canal skin surface of 96 normal-hearing ears of 48 subjects. The main goals of this investigation were to develop a more precise characterization of the relationship between SP and AP amplitudes across normal ears and to determine the confidence limits of this relationship so that a more accurate "normal limit" could be established for clinical testing. The results suggest that the across-subjects SP-AP amplitude relationship is linear. Also, SP scatter increases as AP amplitude increases, but the scatter is equalized by log transforming the data. The distance of the SP from the log-transformed SP-AP estimating line in SE ("AP-normalized SP amplitude") was found to be superior to the SP/AP amplitude ratio as a method of adjusting SP to AP amplitude, because the SP/AP ratio varied significantly with AP amplitude both across subjects and with different ear canal electrode positions.

(Arch Otolaryngol Head Neck Surg 1986;112:759-768)