Acoustics: help on the design of a small Sound Absorbing Cage for rodent sound stimulation

[Joao Bacelo <joao.bacelo@xxxxxx>]

Title: Acoustics: help on the design of a small Sound Absorbing Cage for rodent sound stimulation

Dear All,
 
I’m trying to build a small cage (~20x20 cm (8x8 inch)) for sound stimulation of mice, during neurophysiologic experiments. 
 
The idea is to create a room where the sound (coming from above) will reach the animal the same way independently of its location in the cage (echo reduction).
 
The loudspeaker will be located 50 cm (20inch) above the cage (top is opened). 
And the frequencies used will be in the range of 4 – 32 KHz.
 
-In order to assure the most homogeneous SPLs along the horizontal plane, and to avoid sound distortions, what do you advise me to use as sound absorbing material for the walls and floor? The acoustic foams I found on the market only had noise reduction coefficients tested up to 4 KHz…
 
-And which shape should the cage have? Circular?
 
Thanks for the help.
Best regards,
Joao