Floor Bounce and the messy world of home audio

The late John Dunlavy was castigated on another site for a) being concerned with phase response in his speakers (which I won’t deal with here) and b) not compensating for the “usual” floor bounce (by introducing deviations from anachoically flat in his speakers through the affected range). The purpose here is not to defend Dunlavy particularly, but to look at just one of the many phenomena that affect home music reproduction.

Floor bounce is caused by the sound that bounces off the floor between the listener and the speakers being out of phase at certain frequencies (usually between 100 and 300 Hz.) and partially canceling the direct sound, causing a dip in the frequency response at those frequencies.

Dunlavy’s argument here was that the floor bounce is present in the concert hall so it should be at home, the counter argument was made that the floor bounce is already present on a “properly made recording”, so the floor bounce at home would be double compensation. Sounds reasonable but…

Let’s look at how recordings ARE made rather than how we might WISH they were made. Generally, they employ a) a few mics high in the air and fairly close to the orchestra or b) a bunch of mics quite close to the musicians or c) direct feeds off of musical instrument amplifiers. So they are either far from hall boundaries or very close to the musicians. Given this, it’s safe to say that not much floor bounce is actually caught by the recording mics.

So, if “concert hall realism” is our goal, leaving the bounce in could be seen as necessary to compensate for the missing bounce (as related to a listener’s experience in a hall) in most recordings. So Dunlavy, in that sense, might have been right!

Of course, when we invoke “concert hall realism”, the can is open and the worms are crawling all over the room. Where in the concert hall? Some people like to sit mid hall, some in the back, some in the balcony and some in the first few rows. The sound is quite different, though that is partially compensated for by the fact that it is a live concert and wherever you sit, that comes through. And, on point with floor bounce, that also changes at different location in the hall. How do you compensate for a moving target?

Recording engineers (for various reasons) generally give us a quite close perspective on the orchestra. If the goal, rather than “concert hall realism” is to “reproduce what’s on the recording”, the close perspective is what you should hear, except on those relatively few recordings made from a more distant perspective. Interesting that many who espouse the “reproduce what’s on the recording” philosophy select and set up their speakers to eliminate the room as much as possible, buy a room compensation unit, but set that to a “target curve” rather than flat (now that flat at the listener is something we can accomplish). I know why they do it, and I don’t think it’s the wrong thing to do, but that’s not reproducing what’s on the recording, is it…

The point is that music reproduction in the home is a bit of a messy business and not as simple and obvious as we might like. We will look further into this as time goes on.


Posted on August 19, 2012, in Philosophy and tagged . Bookmark the permalink. Comments Off on Floor Bounce and the messy world of home audio.

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