Ask an expert: Slap echo – what is it, and is it important?

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Ask an expert

Slap echo - what is it, and is it important

I thought you might enjoy a quick update on the progress of the new listening room at PS.  We’ve cleaned out the old room and construction has begun on the new.  Once cleared there are a number of issues that now, while we have a chance, we’re going to address.  One of those issues is slap echo.

If you have time, go to YouTube and watch the video I just launched – covering speaker placement, the Rule of Thirds, the Precedence Effect, and to the point of this post; slap echo.

Slap echo is a term that’s been around for as long as I can remember; so named because to hear the echo you slap your hands together and then listen for the resulting echo.  In the video you can clearly hear the slap echo of our room.

Any time you’re in an empty room give a clap of the hands and listen for the ringing of the clap as it reflects from wall to wall.  With no furniture, rugs or absorption materials in the room, slap echo can be bad.  And make no mistake about it; if you hear this in your room and don’t treat it, your loudspeakers will suffer when they begin to play.

This form of echo is caused primarily from parallel surfaces – of which we usually have 6 of in any one room – and there are a number of ways to fix it.  However, most fixes involve damping the room by adding absorptive materials and objects to the walls and floors.  My preference is to fix the source of this distortion at the heart of it without impairing the reflective qualities of the room.

One such method is to change the room shape by breaking up parallel walls and corners.  Check out the video and after watching you’ll understand this comment:

I built a couple of false corner traps out of doors just to see if the slap echo was affected and bingo!  Perfect.  I have some left at exactly the 1/3 point of the room, but we’ll try and calculate where that comes from next.

Paul McGowan (PS Audio)

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