What Frequency Range Should I Diffuse ? -Acoustics Forum-Acoustic Fields Forum

Dennis,

Are you sure about this? It seems to me that nadeau777 was on the right path with his suggestion.

As far as i know, the very main purpose of phase grating is to keep the energy within the room without disturbing the frequency response, by spreading the energy out in time.

I will have to respectfully disagree with you there Dennis. Specular reflection from one plane will cause peaks and dips in the frequency response, because all the energy will arrive with a specific time delay in respect to the source. Depending on this time delay, some frequencies will cause destructive and some will cause constructive interference, causing peaks and dips.

A properly designed and built QRD will spread that same energy out in time, this will create a more even interference-pattern. There will no longer be certain frequencies where all the reflected energy has a perfect 180deg phase shift caused by a single time delay.