Spatialization 01a

The following simple question has become a test.  I ask it, when I meet Audio People.

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There are two objects:

1) street

2) streetlight

As the player walks around the light, the sound changes, as it does in real life.

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I am speaking to a Unity 3D rep.  I have asked what tools they have, to spatialize objects.  We have gone through the usual misunderstandings.  No, I do not consider line pass-through a "high level" feature.  No I don't mean canned reverb.  I want to use the game environment.

Why don't you tell me what it is that you want to do.  He has twenty years experience as a studio recording engineer.   He is sure he can handle any questions I have.  He sticks his thumbs in his belt, relaxes into it.  He stresses the word, engineer.  I have asked the right person.

It takes him awhile to understand what I am asking.  Not Doppler.  Not panning.  We could walk outside right now and record it.  Eliminate the other variables: Walk in a circle.  Point the microphone directly at it, all the way around.  Record in mono.  The sound of the light still changes as you walk around it.

This is when he scowls.  He has no idea what I am talking about, and he has just put his thumbs in his pants.    His responses are surly.   I have not been rude; I'm excited.  I have used no jargon.  I have reduced the question to its simplest form.  He didn't know it existed.

So I will begin at the beginning:

Stationary Object, Moving Observer

This question is the simplest case of motion in 3-Dimensional space.*  Assume we have a physical space, and a source of some vibration.  Waves propagate in space, from the source.  Assume the geometry is static, and the source immobile.  Integrating and differentiating the field at any one point is no more difficult than another.  The most important reflections for a particular observer position can be precomputed.  Or the the entire field can be baked.

So what are the transforms necessary to render this scene?

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{

*Moving Object, Stationary is {I believe} more complex.  The source of the field moves.  I will visit fields in depth later, when I am not new to them myself.

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