Acoustics

Talk with George Dodd...

Add in some acoustic reflection slots to absorb any potential echo. Make sure the seats are covered with something soft to add to this absorption when people are not present in great numbers.
etc.
Otherwise okay though be aware that circular design can focus the reflections (the above should deal with this).

 

 

 

 

Reverberance

If a sound is stopped, it will not stop instantaneously, but instead your ears (receiver) will continue to pick up the successive reflections until they are completely gone. The louder the original sound, the longer this process takes place. The reflections are caused by sound waves bouncing off  the ceiling, floor, walls.
This gradual dying of the sound wave = reverberation and is one of the most important factors in designing good acoustics for an auditorium. 
The reverberation time = the time the sound takes to fall by 60 dB when the source is stopped (also defined as the time taken by the sound energy to fall to 10-6 of its initial value).

The optimum value of the reverberation time varies according to the different types of sounds like music, speeches, drama, cinema, lecture etc., If the reverberation exceeds its optimum value, then the speech will be completely unintelligible, and if the reverberation is lower than the optimum value the auditorium will be somewhat dead.

Optimal design for reverberation control:

• The audience provides most of the absorption so when the auditorium is vacant or partially vacant the hearing condition will not be satisfactory. To overcome this, use sound absorbing material on the seats so that the absence or presence of audience does not affect the reverberation time.
• Eliminate unwanted echoes, focusing effects of curved surfaces, flatter echoes by fixing sound absorbing materials on the element with the reflective surfaces (ie. Ceiling, walls, floor).
• Side walls should be sound reflecting and diffusing with as many irregularities as possible.
• Large unbroken concave surfaces should be avoided or treated with good sound absorbing materials.

In an auditorium with cushioned seats and a sound absorbing rear wall for echo control, the average ceiling height H is usually H=20T where T is the mid frequency reverberation time in seconds.
Sabine’s formula for reverberation time is used for suitable acoustic treatment. Where ‘V’ is the volume of the hall, ‘S’ is the surface area and ‘a’ is the absorbing coefficient.

Volume
Shape the auditorium so the audience is as close to the sound source as possible, for example a fan shaped auditorium with balconies.