Room Acoustic Descriptors

Hearing is multidimensional, so several descriptors are required when describing room acoustics. They are:


Reverberation is linked to the speed at which sound energy disappears in a room. An unfurnished room with hard surfaces, such as a church, is perceived as being more reverberant than a well-furnished living room.


Long reverberation example: 

Short reverberation example:


Speech clarity 

Speech clarity concerns the quality of speech transfer to the listeners. In a reverberant room with disturbing background noise, it can be difficult to pick up speech. 

The sound that reaches the listener first is called direct sound. This is followed by early reflections. The early reflections that reach the listener within 50 ms are integrated with the direct sound and thus have a positive effect on speech clarity. The reflections that come later may be perceived as disturbing.

 Bad Speech Transmission     VS    Good Speech Transmission



Sound strength

AuditorySound strength is the level at which we experience sound. A reverberant room gives a higher sound level than a room with added sound absorption.


Sound propagation

The sound level decreases as the distance from the sound source increases. The design of the room (shape, furnishing, surface finish etc.) influences the extent to which the sound level decreases along with the distance.