大学図書館のラーニング・コモンズにおける音環境調査

学習・会話活動におよぼす周囲音環境の影響

抄録

 Learning commons (LC) is a space provided in a library to support active learning for users. LC is typically equipped with information technology equipment and space for group discussion so that users can utilize them for exploring information and making discussions. On the other hand, since LC is a space where people are encouraged discussing, acoustic problems may occur such as noise intrusion into other quiet zones or disturbance on concentration of neighboring users in learning due to loud conversation of other groups. However, not many years have passed since the introduction of LC and therefore there are few studies on the acoustic environment of LC.

 In this study, we investigated acoustic environment and user’s subjective evaluation in a LC in a university library by conducting a field survey and acoustic measurement. In the acoustic measurement, referring on ISO 3382-3, a standard for open plan offices, we measured sound pressure level distribution and impulse responses in the LC spaces and obtained spatial decay of speech and speech transmission index (STI). In the field survey, noise measurements, observation and questionnaire survey to users were performed for two days in the LC and a silent zone for comparison. The questionnaire consisted of two questions about learning preference and eight questions about subjective evaluation on spatial impression, including ease of conversation or discussion, noisiness and so on. A total of 541 people responded to the questionnaire in two days. We observed number of users, number of groups, and conversation volume every 10 minutes, and noise levels were obtained every 10 minutes, and these data were connected with the time period of the stay of each respondent.

 Major results are following:

 (1) The noise level in the LC was approximately 45-60 dB, and 30-40 % of the users were making a conversation.

 (2) Answers to the question of preference of learning style and learning environment tended to be different between the users of the LC and the silent zone, such that the users of the LC tended to prefer group learning rather than individual learning.

 (3) User’s subjective evaluations of spatial impression was negatively affected by loud conversations and the existence of loud conversation at the neighboring table affected the evaluation of being bothered and loosing concentration.

 (4) Regarding with acoustics, the spatial decay rate of speech (D_2,s) tend to be high in the space with low height of ceiling compared to the space with high ceiling and this factor affected the decay of STI with background noise.