Speaker
Description
In general, loudness growth functions of normal-hearing (NH) listeners are compressive for medium to high stimulus levels. This compressive characteristic is commonly associated with the nonlinear input-output (I/O) function of the healthy cochlea. The present study investigated the relationship between loudness growth functions and cochlear response functions in NH listeners using psychoacoustic experiments. Listeners had to have pure-tone audiogram thresholds (0.25-8 kHz), tympanometry and stapedius reflexes within normal limits. Categorical Loudness Scaling (CLS) was used to measure loudness growth. The stimulus was a one-second duration speech-shaped noise stimuli. Listeners rated the stimuli on an 11-point categorical scale. Each of these categories is assigned a numerical value referred to as a Categorical Unit (CU). Loudness in CU was converted to sone and a nonlinear function was fitted to the data. Human inferred cochlear response I/O functions were obtained using the fixed-duration masking curve (FDMC) method. The function type was the same as used for the loudness growth function. Correlation analyses were undertaken to understand the relationship between the inferred cochlear measures obtained from the I/O response functions and the loudness growth in sone from the same listeners.