Equal unpleasantness sound pressure levels of pure tones from 10 Hz to 500Hz were obtained by the method of adjustment in which subjects adjusted sound pressure levels equating to subjective degrees of unpleasantness on a 4–steps rating scale. In addition, the maximum acceptable sound pressure levels were measured at each frequency, assuming four types of situations, that is, a living room, a bedroom, an office and a factory. It was found that the acceptable limits were equivalent to very low levels of unpleasantness in some situations. The third order polynomial models of physical variables were well fitted to the subjective response data.
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