Good sound equipment does not improve bad acoustics in a hall. Bad acoustics can be identified by simply clapping in the venue. Listen for any reflections. Poor sound quality will cause fatigue. If the reflected sound is loud enough it will make it difficult to understand what is being said. For those that have a hearing problem, poor intelligibility makes it impossible.
Inside dimensions of the venue can cause problems but more so the materials that are on the walls, floor and ceiling. Please check out this great video by Acoustic Geometry: How Sound Works (in rooms)
Large flat wall areas can be the cause of echo. Hard surfaces reflect sound. The more reflections or echo there is in a hall, the more problems there will be with the quality of the sound.
Consideration should be given to how the hall affects the sound quality. The introduction of soft furnishings can make a considerable difference to improving acoustics.
Heavy curtaining on the platform hung away from the wall slightly will soak up stray frequencies that cause echo and reverberation. Covering glassed areas with curtaining or blinds reduces reflection of high frequencies as well.
There are a lot of manufacturers that provide a variety of resources to assist in designing a venue to reduce reflections.
(Refer to: Autex “Quietspace” Design Guide)
• Hall dimensions need to be optimized- see below
• Acoustic ceiling tiles and not gyprock
• Carpet on the floor and not tiles
• Heavy curtain to stage wall with at least 75 mm gap behind
• Cover large flat walls with sound absorption material
• Cover glassed areas with curtain
The most difficult to adjust are the inside room dimensions. The rule of thumb is that no room dimension should be within 5% of any multiple of another room dimension.
Improving existing building
Replacing a high ceiling with a suspended low ceiling (3 metres) can make a considerable difference. Replacing gyprock with acoustic tiles is one of the most effective environmental changes that can be made to improve the sound because of the large area involved.
Tiles on floors cause reflections. Carpeting these areas or isolating them will will help control this difficult surface. Tiled areas in auditoriums cause major problems. Covering these with a carpet will improve the sound quality.
Carpet on the floor and a curtain on the stage wall is one of the best ways to improve sound quality. The curtain should be made from a heavy cloth type and be mounted away from the wall by at least 50-100 mm to be most effective. Another option is to install acoustic panels on the wall. These panels can be mounted off the wall as well to increase their effectiveness. Partition walls on a slight angle are fine, but avoid angles that reflect sound toward microphones on the stage.
Soft furnishings will assist in soaking up any unwanted reflections of sound.
Door ways are the most common cause of unwanted sound leakage into another room. The use solid core doors and complete door seals will assist in reducing unwanted sound entering the room. Proper acoustic wool laid on the ceiling tiles and installed in the walls will help. The only way to eliminate sound completely is to install a second wall to create an air gap between so sound is not transferred from one surface to the other via the studs and nogging.