2017 年 17 巻 2 号 p. 155-160
Human senses are nonlinear to physical quantities, and a change in a minute stimulus is considered to bring a change in any sense. In the study of tone/timbre, most research considers relatively loud sounds. However, even if the physical characteristics of a tone are similar, the sensory evaluations may differ. For example, in a sound amplifier, although the differences in the physical characteristics are very small, they can be described with the adjectives, “metallic” and “soft”. Usually, specialist evaluations using adjectives are often in agreement. In this study, we examine how minute changes in sound influence a tone. Therefore, the threshold amplitude compression/expansion (ThACE) method for changing the sound in minute ways was proposed. The results of the listening test conducted in this study show the effectiveness of the proposed method. Furthermore, in case of “metallic” and “soft,” the frequency band that influences the sensitivity evaluation was found.