Room Simulation and SBIR

[Avilla]

Hi,

I was looking for an answer for a simple question about REW but I couldn't find it anywhere, so I thought I would ask here in the source.

Is the algorithm implemented in Room Simulation in REW also simulating effects of SBIR (cancellations due physical distance mainly from front wall) - or is it just simulating modal effects of the physical room size?

/Avilla

 

[John Mulcahy]

All sources of reflections are included. The effects of SBIR tend to be overstated because the amplitude of the reflection is often not taken into account. Even with a perfectly reflecting wall the reflection amplitude is much lower than the direct sound due to its greater effective distance from the listener, so the reduction in level at the SBIR frequencies is much, much less than the complete cancellation sometimes described from considering only the relative phases of the direct and reflected sounds.

 

[Avilla]

That’s what I thought, thanks John for confirmation.

And yes, if you have speakers far from front wall then the level of sound bouncing of that wall is lower, and when you have speakers close to the wall then reflections can be a little bit higher, but due to the directivity of higher frequencies the amount of sound going toward front wall („from back” of the speakers) will be lower. All and all the worst case is in the middle - when you have speakers ca. 1-1.5 m then this effect may be quite noticeable.

Br, Avilla.