The purpose of this study is to clarify the relationship between comfortable sound environments inside residences and the average sound absorption coefficient of an individual room. To accomplish this, psychological experiments were conducted using actual scale room models, and the acoustic characteristics of several rooms in actual residences were investigated. As a result of these experiments and investigations, the following points have been clarified: 1) The average sound absorption coefficient affects the comfortable sound environment of residences. 2) The psychological items affected by the average sound absorption coefficient are “sense of silence”, “sense of reverberation”, “feeling of serenity”, “sense of quality” and “user preferences”. 3) Higher average sound absorption coefficients reduce the “sense of reverberation” and increase the values of the other psychological items.
