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Dynamic attenuation for a source to silence when moving out of the speakerfield

Spat
#1

This might be an obvious question, I apologize if so, but I found that for all panning algorithms once I move a source beyond a speaker in the direction of a speaker (so let’s say positioning behind a speaker in physical space) the source remains at equal level.

For example if I have a speakers with coordinate (xyz)-1 0 0 if I move the source from the origin to this coordinate it will gradually increase as expected, with curve depending on the algorithm, but once I move the source beyond the speaker in the same direction so let’s say to cordinate -3 0 0 the source will stay equally loud on this speaker as if it is still on the same coordinate as the speaker. Is there a way to activate a sloping once the source moves outside the field and beyond the speaker? I have experimented with the spead and radius of the sources but this is only effective when source is inside the speakerfield.

I would like to have a flock of birds moving into the speakerfield and was wondering if it is possible to have them fly in sloping towards the speakers from silence to full range signal :slight_smile:

Thanks for the advice,
Robin

Binaural attenuation to zero
#2

Hi Robin,

I presume you are using spat5.pan~
This object implements various panning algorithms, and they do not take the distance into account (only the azimuth and elevation of the sources are relevant).
A notable exception to this rule are the “knn” and “dbap” algorithms which are fundamentally distance-based.

Spread essentially controls the angular extent (or width) of the source; so, not related to distance either.

If you want an attenuation law with respect to distance, you can use the spat5.spat~ object instead. The attenuation “slope” is controlled by the so-called drop factor. (cf spat5.oper)
Alternatively, you could implement your own distance law by applying a gain factor to the source signals.

See also this thread for a somehow similar question.

Best,
T.

#3

Thanks for the quick reply Thibaud,

I was now in the process of working on a formula to implement a distance variable by applying a gain factor to the source signals indeed as your final suggestion done, but with this new information I will also look into spat5.spat~ drop factor also, thanks for pointing this out. My observations were initially based on spat5.pan~ indeed.

Best,
Robin