In this study, the subjective experiment was carried out using the description terms of the quality of the different classes in ISO/WD TS 19488 on low-frequency rubber ball impact sound standardized in the ISO as the heavy/soft standard impact source. Experimental condition of 3 times experiments consisted of different background noise and task conditions. In addition, a questionnaire survey on the noise sensitivity and opinion of neighbours of each subject was conducted. The response differ-ence became larger when the presented rubber ball impact sounds more loudly. When subjects carried out internet surfing in high background noise condition, the level differences between groups were decreased in both cases. These results mean that noise sensitivity of subjects influence more in the low background noise condition and the influence became smaller when background noise increasing and concentration on the presented sound interfered by carrying out a task. Noise sensitivity was influencing when subjects hear clearly the presented sound, but when subjects were interfered con-centrating on the presented sound by an external condition such as background noise or other tasks the effect of noise sensitivity can be decreased clearly.
