Frequency selectivity: reliability of electrocochleographic measures with iso-intensity masking

In a group of 12 normal or hearing-impaired subjects, frequency selectivity was determined psychoacoustically and electrophysiologically with the fast ECochG iso-intensity masking procedure, using a 4 kHz test tone and simultaneous pure-tone masking. Psychoacoustic curves measured twice for each subject were reproducible and showed a broadening related to hearing loss. The curves determined with ECochG repeated two or three times for each subject varied greatly for half of the subjects and their widths were not related to hearing loss. ECochG measures were reproducible in the cases where the amplitude of the response was larger. The data set out the conditions and limits of this ECochG procedure for clinical use.