Abstract
Some of recent hearing aids are featured with level compression circuits to compensate the recruitment. Gains of such a hearing aid for a specific input level at a frequency should be so determined that the loudness of the input for a impaired subject becomes as much as that for those with normal hearing. Therefore, it is important to estimate loudness functions, which describe loudness growth as a function of input signal level correctly. In this paper, application of the rating scale method for estimating loudness functions is considered. In particular, subdivision (two-step) rating scale method was focused on. First, Japanese adverbs and adjectives to represent rating scales that ranges from the threshold of hearing to UCL were examined. Next, loudness functions were measured with the subdivision rating scale method. The results of the subdivision method were compared with those of the conventional (single-step) method by regarding subjects judgments at the first step of the subdivision method as the result of the single-step method, and showed that the variance of the result of the subdivision method was smaller than that of the single-step method.
