What is reverberation time?
Reverberation time is a concept that often comes up when talking about acoustics. Sound waves are produced and propagate in all directions. When the sound wave comes into contact with a surface, some of the sound is absorbed and some is reflected. The harder the surface, the greater the percentage of sound reflected. The reverberation time is the time it takes for the sound pressure level in a room to drop by 60 dB from its maximum (initial) value. Closed rooms with "hard" walls and floors (such as concrete, laminate, etc.) have poorly absorbing surfaces and therefore a long reverberation time.
How is reverberation measured?
The amount of reverberation is expressed in reverberation time in seconds. In general, the longer the reverberation time, the worse the acoustics. To measure this, a sound meter and a "bang" using a specially designed gun are usually used.
What is the desired reverberation time in my situation?
The desired reverberation time is strongly dependent on the use of the room, among other things. A call centre, for example, needs a different reverberation time than a recording studio. Below are the required reverberation times for a number of rooms:
- Office: 0.5 - 0.8
- Restaurant: 0.5 - 0.7
- Office garden: 0.4 - 0.5
- Sports hall: 1.2 - 1.5
- Lecture room: 0,5 - 0,8
- Practice room: 0,6 - 0,8
What are the consequences of a long reverberation time?
A long reverberation time and poor acoustics result in poor sound quality and speech intelligibility. This causes people to drown each other out, sound to spread and the noise level to rise in a room. Poor acoustics can lead to fatigue, headaches and, in the long term, stress. In addition, poor acoustics have a negative impact on work productivity.
How can reverberation time be improved?
The reverberation time in a room is improved by adding sufficient sound absorption to a room. This absorption should be well distributed in the room and preferably placed as close to the sources as possible. In this way, specific reflections can be counteracted.