A pilot study on adequate sound levels for acoustic signs for the visually impaired

Abstract

Acoustic traffic signals and the entrance chimes of public buildings are the two most common auditory signals for the visually impaired in Japan. However, there are currently no standards established for the sound levels of these signals. Thus they are set by ad hoc rules. Therefore, it is desirable that what are adequate sound levels be determined for these signals. This study used a psychoacoustical experiment to investigate what were adequate sound levels. Recorded environmental sounds and auditory signals were played simultaneously via headphones, and the visually impaired participants were required to adjust the sound level of each acoustical signal to an adequate level. Results indicated that the participants' strategies for adjusting the sound levels could be divided into two groups; one that adjusted the sound levels of the auditory signals through a comparison with the maximum environmental sound, and one that adjusted the sound levels according to the normal status of the acoustic environment. We determined that adequate sound levels for acoustic traffic signals should be estimated by comparing them with the estimated highest sound levels. On the other hand, for entrance chimes, adequate sound levels can be satisfactorily estimated by comparing them with normal sound levels.