A Guide to Auditorium Acoustics

Auditoriums are big rooms with lots of hard surfaces. Concrete, plaster, glass, timber and hard seating all reflect sound. If there’s not enough absorption, sound keeps bouncing around the room.

The most common problems are:

• Long reverberation times that blur words and music together
• Sound reflecting off the back wall and back towards the stage
• Flutter echo between parallel side walls
• Uneven sound, with some seats sounding clear and others sounding boomy
• Noise build-up when the audience is talking before and after events

Good acoustics means sound is clear and even across every seat. Some reflection is helpful because it carries sound to the back of the room and gives music warmth. The aim is to control it, not remove it.

The key measure is reverberation time (RT60), which is how long it takes sound to fade away. The right target depends on how the space is used:

• Speech-focused spaces (lecture theatres, conference venues, school halls) need a shorter reverberation time so words stay clear.
• Music-focused spaces benefit from a slightly longer reverberation time, which gives sound richness.
• Multi-use spaces need a balance that works for both.

Our guide to reverberation time explains how RT60 is measured and what the numbers mean.

Placement matters as much as the product you use. The areas that usually make the biggest difference are:

• The rear wall. This is the surface most likely to send an echo back to the stage.
• The ceiling. In large or high spaces, the ceiling is usually the largest reflective surface.
• Side walls. Treating parallel walls stops flutter echo and evens out sound across the seating.

Every space is different, so an acoustic survey is the best way to know which areas need treatment.

Fabric Panels

Fabric panels such as Silent Space absorb sound across a wide range of frequencies and come in a wide choice of colours and fabrics. They work well on rear and side walls, and can be arranged to suit the rooms design.

Ceiling Rafts and Baffles

Acoustic rafts absorb sound from above, treating the biggest reflective surface. Controlling sound reflections from the ceiling is crucial for maintaining speech clarity. They can be suspended at different heights to work around services and are available in a range of shapes, colours and sizes. Baffles can also be used; they are ideal for spaces with very high ceilings or where services need to stay accessible.

No. Acoustic panels reduce echo and improve clarity inside the auditorium. Stopping sound from getting in or out is soundproofing, which is a different job that involves the building’s structure. Our post on soundproofing vs acoustic treatment explains the difference.

Treating the wrong surfaces. Panels placed at random won’t fix the problem and may miss key areas that need treatment.

Over-treating the space. Too much absorption makes a room feel flat and lifeless. It can also make it harder for sound to reach the back rows.

Relying on the sound system. Turning the sound system up doesn’t fix reverberation and often makes it worse.

Forgetting the ceiling. In large rooms, walls alone rarely provide enough absorption.

We’ve treated auditoriums, lecture theatres, school halls and performance spaces across the UK. We’ll measure your space, recommend a scheme that suits how it’s used and supply and install everything.

Book a survey