Ever heard a speaker barely audible in an auditorium while attending a lecture or play? Probably poor acoustics were to blame. Be sure to take into account these 7 key factors when designing, building, or reviewing an auditorium.
The Acoustics of Auditoriums
The location of new auditoriums should be made as far away from highways, railroad tracks, and industrial areas as possible. There may be particular problems with airport noise in some locations. To prevent disruptions within the auditorium, conduct an Auditorium Sound Study prior to construction.
2. Areas around Auditoriums
Build buffer zones to isolate the auditorium from the rest of the building and noise sources—place hallways and lobbies between the auditorium and restrooms, mechanical equipment, dressing rooms, etc. In the space surrounding the auditorium, offices or storage should be located while it is not being used.
3. Doorway STC
A solid-core door should have airtight seals to prevent outside noise from getting in. Performance spaces should be fitted with STC-rated doors. Door performance of STC 35-40 is recommended even though apartments might only need STC 32. Make sure that the center of the double door has an Astragal and that there is sufficient rubber gasketing to prevent the doors from being flanked.
4. Reverberation Analysis for Auditoriums
Reverberation in a large room can be reduced by:
Utilize sound-absorbing materials in the walls and incorporate sunken panels, undulations, and irregular shapes
Consider customized and installed stretch fabric wall systems for auditoriums as a specialty treatment
Most of the construction should be done with sound-reflecting materials such as thick wood and thick gypsum (concrete).
You can minimize the hard surfaces on walls by hanging thick fabrics.
A carpeted aisle helps reduce the noise caused by foot traffic.
Fabric seating is always the best choice. Do not use metals or plastics.
Layout the ceiling in a checkerboard pattern alternating between sound-absorbing and sound-reflecting materials.
In basic acoustic analysis, the reverberation time in space is determined simply by ascertaining the room’s geometry and the amount of sound absorbed in the room.
Analyzing the reverberations of a sound- basic assessment
To conduct more advanced analysis, specific frequency bands have to be analyzed, usually in 1/3rd octave bands. Auditoriums and other venues that require further customization may require this.
Reverberation assessment using advanced techniques can also be done, for example, auditorium background noise.
5. Auditorium Background Noise
Reduce HVAC noise by installing sound-absorbing duct liners and mufflers. In HVAC design, the NC (Noise Criteria) level should be at or below NC-35. NC level 40 may be required for critical spaces.
If your acoustic consultant or mechanical designer prefers dBA levels, NC levels can be compared.
6. Balcony Design
Wherever possible, balconies should be provided so that the distance between the stage and the furthest seats are minimized. Sound absorbing material should be used in the overhang and it should be of a small depth.
7. Auditorium sound systems
Speakers should be positioned just above and behind the proscenium opening. Instead of being placed in a separate room at the back of the auditorium, the controls should be situated in a central location of the seating area.
8. Orchestra Pits
The conductor should be able to open and close soundproof curtains to control the sound level if there is an orchestra pit in the auditorium.
The general public can listen to a wide variety of events and performances in general auditoriums, but if audiences cannot hear them, the events will not succeed. You should keep this list in mind next time you need to design the perfect acoustics for a general auditorium.