With an unexpected reverberation in his voice Pierre rapidly began:
In all cases, therefore, where it is desired to do the work out of contact with the solid fuel, the operation of burning or heat-producing must be performed in a special fire-place or combustion chamber, the body of flame and heated gas being afterwards made to act upon the surface of the material exposed in a broad thin layer in the working bed or laboratory of the furnace by reverberation from the low vaulted roof covering the bed.
Consider a soft wall surface: Hard walls that are all the same length can wreak havoc on sound quality because the sound bounces around from hard surface to hard surface, creating reverberation and harsh noise.
For occupant comfort, the internal relative humidity had to be maintained at about 55 %, which significantly increased the reverberation time.
They can also be fitted directly to walls to reduce reverberation.