The sound level of the auditory guidance for operating a copier machine must be carefully determined so that it will be intelligible above the sound of the copier itself. In this study, a psychoacoustic experiment was conducted to determine a suitable sound level, using persons of normal healthy and visually disabled persons as listeners. Measurements showed that when the equivalent continuous A-weighted sound pressure level of the copier machine in idle mode was 44 dB, the auditory guidance level adjusted by listeners ranged from 48 to 59 dB. When the level of copier machine sound in operating mode was 66 dB, the auditory guidance level adjusted by listeners ranged from 61 to 68 dB. The average of visually disabled persons was 4dB higher than the average for normal healthy persons in idle mode. However we did not find any statistical significance between them. Optimum sound levels of the auditory guidance for operating copier machines were thus derived.

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