Fast psychophysical tuning curves of the cochlea in normal hearing individuals

Abstract

Introduction Fast psychophysical tuning curve (fPTC) test is a fast computer-based method that aims to assess the frequency selectivity of the cochlea and to detect the dead regions. It can quickly identify tip frequency and Q10 of psychophysical tuning curves (PTCs) derived by using a band of noise that changes in center frequency and a Bιkιsy method to adjust the masker level required for threshold of the noise. We applied this method in normal hearing individuals in the presence of threshold equalizing noises at three signal levels. The sharpness of the PTCs (Q10) and the typical shift of tips of the PTCs for 16 normal hearing individuals, when the tip frequency is estimated for the average of a forward and reverse sweep, were obtained. The results were used to determine the mean, SD, and 95% confidence interval of the shifts in normal hearing individuals. Objective The purpose of this experiment was to estimate the typical shift of tips of the PTCs for normal hearing individuals. The results were used to determine the mean, SD, and 95% confidence interval of the shifts. The sharpness of the PTCs change with signal level under conditions where off-frequency listening is restricted, using a background noise, was also assessed. This was performed to allow a comparison with the results of hearing-impaired patients tested at the same level (but without background noise). Study design Sixteen adults of both sexes (eight male individuals and eight female individuals) were randomly selected to establish normative data for the fPTC test. They were selected with age ranging from 18 to 45 years. All individuals had normal middle ear function as indicated by tympanometry and acoustic reflex measurement and by hearing threshold equal to or better than 20 dB at octave frequencies in the frequency range (250-8000 Hz) (as defined by ANSI S3.6-2004).