音環境に着目した保育施設の実態調査

Abstract

A conducive acoustical environment for children is considered essential to support healthy growth. However, the significance of acoustical quality in nursery facilities has not been fully recognized in building design. Further, the management and types of nursery schools are now diversifying and various acoustic disturbances such as excessive noise in the environment or reverberation are often noticed. At present, the architectural Institute of Japan (AIJ) indicates the guidelines for acoustical properties of schoolrooms for elementary schools, as well as junior and senior high schools. AIJ is also working to extend the guideline for schoolrooms to nursery facilities and preschools. Against this background, the study conducted a field survey across twelve nursery facilities to assess the status of acoustical environment. The survey observed the division of spaces for each age, the dimensions of and finish on surfaces in rooms, and children's activities conducted within them. Additional information was collected on the background and characteristics of each facility, the users' evaluation of facilities, and evaluation of the acoustical environment in nursery rooms. Noise levels and reverberation time were measured in four facilities, and a management system to maintain a comfortable sound environment was observed in one facility. The survey on the division of spaces for each age group indicated that in most facilities, the nursery rooms were designed with poor acoustical separation. A typical case of successive nursery spaces was observed in a rented room in a part of the building. Here, the successive spaces were divided by low shelfs or fences, and groups of different ages engaging in different activities shared the sound environment. Additionally, some nurseries were characterized by mixed-age grouping activities and spaces were set not by ages but by activities. Movable partitions and sliding doors were installed to ensure flexible use of spaces according to the activities. Connectivity between spaces was found to facilitate cooperation, but was detrimental to the sound environment. As observed in the survey, such “mono-spaces”—connected rooms without sufficient sound insulation—may cause acoustical problems. As some teachers mentioned during their interviews, there were instances of acoustical disturbance due to voices from other groups. The survey found sound-absorptive materials in use in only a few of the facilities visited. Long reverberation times were measured in nursery rooms without absorptive materials, especially those with a high ceiling and those organized as successive spaces. Another typical problem was noise exposure attributable to the ventilation system and site location such as underneath elevated railway tracks. In nursery facilities, the effects of noise should be considered not only in the context of speech communication, but also in the context of sleep disturbance during naptime. It was observed that a management method to maintain a comfortable sound environment was important. In one nursery facility, nurses pursue the concept of “break away from the noise” and participate in a training session every year. The facility also inculcates practices of gentle vocal communication, and measurements showed lower levels of sound generation during activities. The results of this study indicate considerable differences between the acoustical environments in nursery facilities and school buildings. It is hoped that the findings of this study will be taken into consideration while formulating guidelines for acoustical environments in nursery facilities. It is also necessary to diversify the method to improve acoustical environment through additional absorptive treatment and effective management to maintain a comfortable sound environment.