Subjective Effects of Sound Absorption and Investigation of Reverberation Times in Modern Japanese Dwellings

Kazuma Hoshi,Toshiki Hanyu,Ryoichi Suzuki,Daisuke Watanabe

doi:10.3390/app11062709

Abstract

This study aimed to reveal the influence of sound absorption in general dwellings on the subjective evaluation of acoustics. First, a subjective experiment was conducted using a full-scale room model. The results indicate that the feelings of silence and serenity can be experienced at absorption coefficients above 0.17, particularly above 0.25. Additionally, we used the recorded binaural sounds for a subjective test instead of using a full-scale room model. This trial showed that the reverberance, feeling of silence, and feeling of serenity can also be evaluated using a headphone listening test. We also measured the reverberation times and recorded the sound environments in three bedrooms, three living and dining (LD) rooms, and three child rooms in modern Japanese dwellings. The average absorption coefficients of the LD and child rooms were lower than 0.17, in the range of 500 Hz to 4 kHz. Therefore, we analyzed the subjective effect of absorption through a psychological test using binaural recorded sounds. The bedrooms with absorption coefficients of 0.18–0.23 were significantly less reverberant, quieter, and more serene than the other rooms.

Highlights

Wooden dwellings are very popular in Japan because most part of the territory of the country is covered by forests and mountains
The values of the living and dining (LD) rooms did not differ among the three houses
The high absorption coefficient values at 125 and 250 Hz were due to the panel absorption of the walls and ceilings

Summary

Introduction

Wooden dwellings are very popular in Japan because most part of the territory of the country is covered by forests and mountains. With the change in Japanese lifestyle, cloths on plaster boards have been used for the finish of walls and ceilings, instead of thin wooden boards, whereas for the floor, wood is commonly used instead of “tatami” (straw and rush mats). These changes may lead to longer reverberation times and higher average sound pressure levels in modern Japanese dwellings. Under these circumstances, Japanese dwellings could be expected to require different specifications with respect to airborne insulation from the outside and room acoustics

Objectives

Methods

Results

Discussion

Conclusion