Even the iPhone's measured 50 ms must be clearly detectable (I don't have one, so can't check).
A trivial example - have an app with a picture of a snare drum that when tapped will play a sound of such drum. It's well known f the delay beteen physical touch is more than, say, 20ms - then it will sound "not instant", the sound will be perceived by your brain as a separate event; and even 10+ ms will feel delayed to any drummer.
A trivial example - have an app with a picture of a snare drum that when tapped will play a sound of such drum. It's well known f the delay beteen physical touch is more than, say, 20ms - then it will sound "not instant", the sound will be perceived by your brain as a separate event; and even 10+ ms will feel delayed to any drummer.