“The day when noise is of an average situation for the year” is selected for evaluating environmental standards concerning noise. Therefore, it is necessary condition that the selected measurement day is close to the annual average value, small deviation and accurate. If the measured value observed is divided for every element, such as moon and day of the week, and the day with both a small deviation and an average value close to the annual average value is the selected measurement day, an accurate representational value can be acquired. From this point, we examined the continuation measurement results over a long period of time on some city using the statistical technique of distributed analysis or cluster analysis. Consequently, we acquired the knowledge of the measurement day for the suitable representational value.
In the general residential areas, although these areas are not faced the sound sources such as main roads, railroads, and construction works, there are various kinds of sounds. In this research, it thinks that the sound environment of areas can be grasped by exploring the memory about the sounds stored in the consciousness of the residents who live in these areas. And reconfirmation of various sound sources is verified about the possibility of using it as an evaluation index of sound environment. First, the sound source is classified according to the degree of good will to sound, and the index sounds are selected. Next, the questionnaire is performed to the residents of Yokohama city and the relation of the degree of recognition of index sounds and the index which shows the characteristic of a place-of-residence region, the degree of satisfaction to habitation environment is considered. Consequently, it is shown that the degree of cognition of index sounds may serve as the new way of evaluating the sound environment in a general place of residence.