Annoyance and discomfort during exposure to high-frequency noise from an ultrasonic washer.

Annoyance and discomfort during exposure to high-frequency noise from an ultrasonic washer have been examined in the experiments carried out with 10 subjects. After a short exposure during which the subjects rated their annoyance and discomfort, a broad-band noise was matched to the ultrasound. The subjects were exposed to three different levels of ultrasound on three different occasions. Analyses showed that ultrasound causes considerable annoyance and discomfort even for the lowest exposure levels. No significant difference between annoyance and discomfort was observed. The matchings indicated, however, that the A-weighting, i.e., the traditional rating technique used for noise evaluations, overestimated the high-frequency sound when evaluating annoyance and discomfort.