Abstract
The auditory masking of low-frequency sound by pure tones and band noise was measured. Forty subjects participated in our experiments. There was not much variation among the subjects in the masking by pure tones but there was a large variation among them in the masking by band noise. The masking characteristics of band noise were investigated. The frequency characteristics of the masking by band noise could be divided into three groups of subjects by cluster analysis. The first group of subjects had masking values that were positive or small at all frequencies. The second had masking values that were negative or small at several frequencies. The third had masking values that were positive at frequencies lower than 20 Hz and negative at frequencies greater than 20 Hz; the curve of these values having an inverse S shape. To find the reason as to why the subjects could be divided into a few groups according to the masking characteristic, psychological experiments were performed. Twenty-one sound stimuli, – pure tone, band noise and both pure tone and band noise – were prepared. The subjects belonging to a particular group had similar psychological responses to the sound stimuli. Many people do not complain about low-frequency sound but some people are suffering from it. The people who sensitively responded to low-frequency sounds are reported. The results obtained here may explain the special relationship between the sufferers from low-frequency sound and the hearing characteristic.