• Reverberation time is the primary descriptor of an acoustic environment.
• A space with a long reverberation time is referred to as a "live" environment. When sound dies out quickly within a space it is referred to as being an acoustically "dead" environment.
• An optimum reverberation time depends highly on the use of the space.
• For example, speech is best understood within a "dead" environment, while music can be enhanced within a "live" environment as the notes blend together. Different styles of music will also require different reverberation times.
• In order to provide a reproducible parameter, a standard reverberation time has been defined as the time for the sound to die away to a level 60 decibels below its original level

Size:

• Reverberation time is affected by the size of the space and the amount of reflective or absorptive surfaces within the space.
• A space with highly absorptive surfaces will absorb the sound and stop it from reflecting back into the space. This would yield a space with a short reverberation time.
• Reflective surfaces will reflect sound and will increase the reverberation time within a space.
• In general, larger spaces have longer reverberation times than smaller spaces. Therefore, a large space will require more absorption to achieve the same reverberation time as a smaller space.
• In some theatres, the music continues for a short time even after the musicians have stopped. This continuation of the music is due to echoes.
• In a well-designed concert hall the reverberation time is at most 1s or 2s. If reverberation times for a concert hall are too long, the sound quality is reduced.

Nature of wall’s surface:

• Reverberation time is the most important factor of sound quality in a concert hall.
• You can change the reverberation time by changing the texture or materials of the wall, ceiling and floor coverings and even changing the furniture.
• When designing a concert hall with reverberation time in mind, factors such as the length of the hall, the height of the ceiling, and the slope of the floor and ceiling must be considered.
• Materials such as brick and concrete reflect sound easily and increase the reverberation time due to subsequent echoes.
• The floors and walls of auditoriums are thus lined with very carefully selected materials to reduce undue reflections.

Audience:

• One factor that must be considered in auditorium design is the effect on its reverberation time due to the audience.
• since the sound absorption of an average human being is about 4.5 Sabine, variations in the size of the audience may produce significant changes in the reverberation time