Numbers:

So in pratice you need for an reactive Audiosystem for

• BigHallConcerts: < 30ms
• SmallBarsConcerts: < 20ms
• StudioMixing < 10ms ???
• ScientificPurposes <= 0ms ???

(Comment: Isn't Pd's latency just added to the room's latency??? --Frank Barknecht)

How to get this numbers

Big Hall Concerts

Having a big Hall where speakers are up to than 33m from each other the time difference is 100ms for them. But normally if you think about an orchestra which has 10m distribution of musicians the time between the musicians is about 33ms.

So I think having a latency of 30ms should do.

SmallBarsConcerts

Use cases:

• mixing live signal through pd
• effects
• MIDI-Synths

Normally you dont hear time differences below 10 ms on percussion stuff so I think this is enough.. But you have to do the mixing complete through pd (havin same latency on all signals, Microphone) otherwise there are comb filter effects, playing through the speakers.

Experience:

When using liveeffects and mixing through pd, it is very disorientating if you have a latency more than 20ms, just tested it and feeling not good having this to improvise.

StudioMixing

Use case:

• mixing pd into the stuff (aux out -> pd -> line ins)
• effects

depends on the effect, but if you mix with a live signal on your mixingconsole having latency causes comb-filter effects and so on. so normally very small latancy is good < 10ms ???

Scientific Purposes

Use Cases:

• Noise Cancelation

  can be done down to the size of the speaker (point wave) so pratically since of wind temperature changes sound speed etc... until 300Hz -> 3ms

• adaptive filters (if you want to react to live signals) < 10ms
• sample to sample processing -> 0ms