Re: Mixing it...


Subject: Re: Mixing it...
From: Lonce LaMar Wyse (lwyse@krdl.org.sg)
Date: Mon May 24 1999 - 19:36:30 EDT


Hi Kevin,

   I am a bit confused by the "followed by" in your description, but
   roads and lakes are great reflectors that create a secondary path
   from the sound generator to your ears that is slightly longer than
   the direct path. This creates a periodicity (rather like a comb
   filter) in what you hear that is related to the difference in
   arrival times for the two paths.

   If the sound source is moving toward you, the difference between
   the lengths of the two paths is getting longer and the pitch seems
   to drop. As the source passes you and moves away, the difference
   between the two paths shrinks and the pitch rises.

   I don't know that this is what you were hearing, but what I
   describe is easy to hear as a jet or airplane passes by
   overhead. In fact, for simulating some sounds such as the jet
   fly-by, the secondary reflection path is key for realism.

- lonce



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