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Re: Muddy 3D mixer
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Re: Muddy 3D mixer


  • Subject: Re: Muddy 3D mixer
  • From: Chris Rogers <email@hidden>
  • Date: Mon, 16 Sep 2002 11:26:35 -0700

Tim,

The muddiness that you're hearing is the air absorption effect, filtering
out higher frequencies at large distances. It sounds like you would like
a way to turn this off, independent of the doppler shift effect, etc.
Currently there is no way to do this, but we could add a property to the
mixer to allow it to be disabled on a per-channel basis..

Chris Rogers
Core Audio Engineer
Apple Computer



So, I'm trying to empirically measure the falloff curve in the 3D mixer and I have an app where I have two sets of mixer parameters (azimuth, elevation, distance and gain) and a looping sound and a button to switch between the two sets of parameters.

Now, if I put one set at zero distance and zero gain (i.e., play the sound unaltered), it sounds like it should. But, if I play a sound way out in the distance and then up the gain to try to get the same perceived volume, the sound is really muddy. I'm not putting any sort of effects processor in the audio unit chain and I get the same effect whether I use HRTF, SoundField or VectorBasedPanning as the spatialization algorithm.

In all cases, the sound is positioned directly along the ray pointing directly in front of the listener.

What gives?

-tim
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References: 
 >Muddy 3D mixer (From: "Timothy J. Wood" <email@hidden>)

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