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Panning a Plane Source onto a Plane Channel Configuration


[Note] Note

For context, please reference the first example.

So far we have only seen flat sources (4.0, no height channel) and flat output channel configurations (5.0) from above. Here we go again, but with perspective. Note that it is the projection of the virtual sources coordinates on the speakers' plane that is used to compute panning.

In the middle column of the figure below, Rotating the Listener Up, we show what happens when the listener looks up (towards the sky) by 30 degrees. The fact that the listener rotates has an impact on:

  • the relative orientation of the emitter sound field (as seen with 100% Spread); and

  • the incident angle of the point source (as seen with 0% Spread).

This is why the point source (0% Spread) ends up below the Center speaker.

In the right column, Rotating the Emitter Down, we rotate the emitter by 30 degrees down, instead of the listener. This only has an impact on the relative orientation of the emitter sound field, but not on the incident angle of the point source. Consequently, with 0% Spread the point source is right in front of the listener, not below it like in the middle column. Notice how virtual sources morph differently from 100% to 0% Spread.

Panning of a 4.0 Source on a 5.0 Channel Configuration, with Various Spread Values

Spread

Rotating the Listener Up

Rotating the Emitter Down

 

100% Spread

50% Spread

0% Spread

Proceed to the next 3D positioning example: Effect of Height Spread.