ゴムボール(JIS A 1418-2衝撃特性(2))による重量床衝撃音の予測方法に関する検討

最大A特性音圧レベルの予測

田中 ひかり^＊１・田端 淳^＊１

集合住宅の床衝撃音遮断性能のうち，重量床衝撃音遮断性能は床の仕上げ材によって改善することは難しく，スラブの厚さや寸法など躯体の構造によって凡その性能が決定する。したがって設計時に予測を行い適正なスラブ厚などの設定を行うことが重要である。
現在の床衝撃音の測定で主に使用される衝撃源はタイヤ（衝撃特性(1)）であり，バンド最大音圧レベルと評価基準との比較により評価値を求める。しかし，日本建築学会などでは衝撃源としてゴムボール（衝撃特性(2)）を積極的に用いていこうとする動きが見られる。評価方法は未定であるが，最大A特性音圧レベル（L_Amax）が用いられることが示唆される。そこで，L_Amaxによる予測の可能性を探るため，現場で実測したデータを用いた検討を行った。
その結果，実測値と3dB以内の差で予測できた。また，A特性の補正を行う際のバンド幅や，取り扱う周波数範囲の選定が予測精度に大きく関わることが分かった。

＊１ 技術センター 建築技術研究所 環境研究室

Calculation of Impact Sound Insulation of Building Floors with Heavy/Soft Impact Source

Prediction of A-weighted Maximum Sound Pressure Level

Hikari TANAKA ^*1 and Atsushi TABATA ^*1

The importance of insulating apartment building floors against heavy impact sources has increased. Impact sounds caused by light impact sources can be reduced by floor coverings, but this is not the case with heavy impact sources. Insulation performance is governed by several factors, such as the thickness of the concrete slab, the distance between beams and rooms, and other structural characteristics of the building. It is therefore very important to estimate insulation performance for impact sounds prior to construction.
A rubber ball has been included in the Japan Industrial Standards (JIS) as a heavy/soft impact source since 2000. It is expected that rubber balls will be broadly used together with conventional small automobile tire sources.
Floor impact sound pressure levels are measured per octave in JIS and evaluated by comparison with rating curves. However, it has been reported that for floor impact sounds, the A-weighted maximum sound pressure level (L_Amax ) and the sound perceived by humans are in good correlation. Application of L_Amax is therefore expected for rating impact sound insulation performance.
In this study, L_Amax values for heavy impact sounds caused by a rubber ball are calculated, and compared with measurements. The difference between predicted and measured L_Amax is smaller than 3 dB. The proposed method for calculation of L_Amax therefore shown to be applicable to prediction.

*1 Environmental Engineering Research Section, Building Engineering Research Institute, Technology Center

44 - REPORT OF TAISEI TECHNOLOGY CENTER 2008 No.41