公認的定義是：聲能密度降為原來的1/10^-6時所需的時間，相當於聲壓級衰變60分貝。某頻率的混響時間是室內聲音達到穩定狀態，聲源停止發聲後殘餘聲音在房間內反覆經吸聲材料吸收，平均聲能密度自原始值衰變到百萬分之一(聲能密度衰減60dB)所需的時間，用T60或者RT表示。混響時間過短，聲音發乾，枯燥無味，不親切自然；混響時間過長，會使聲音含混不清；合適時聲音圓潤動聽。
Here is an example from United Kingdom
Calculating volume for mass of 50-seat Small Recital Room
· Reverberation Time (RT provided by ARUP)
· Volume (m3)
· Seconds (s)
50-seat Small Recital Room = 1.4s RT.
1m3/seat for every 0.2s RT = 1.4/0.2 = 7m3
7m3/seat = 7 x 50 = 350 m3
Divide 350 into Width x Length x Height to work out approximate size
of mass. For example 7W x 10L x 5H = 350m3
(For curved/angular geometry specifics, ask ARUP)
Calculating volume for mass of 150-seat Small Concert Hall
· 1.7s RT (provided by ARUP).
· 1m3/seat for every 0.2s RT = 1.7/0.2 = 8.5m3
8.5m3/seat = 8.5 x 150 = 1275 m3 (divide into Width x Length x Height)
Example 1: 10W x 12.750L x 10H = 1275m3
Example 2: 12W x 16L x 6.641H = 1275.072 = 1275m3
(For curved/angular geometry specifics, ask ARUP)
