I’m not convinced that article is entirely right, although it does say that tolerance varies, and people notice it or are more intolerant of it with IEMS compared to wedge monitors (which, in theory, should always have worse latency than IEMs).
I’m not sure it destroys your ability to play on the beat with a drummer, but I definitely think there’s a point where it starts to affect it. I think most musicians can adjust (which is, effectively, what we are constantly doing with bell ringing as we have a latency of around 1 full second and have to wait around 2 seconds before we can make adjustments for a particular error, as there are two strokes) but, for a normal musical instrument, I think it starts to feel a little off.
As an example, I’ve done some online jamming with Jamulus where the latency was around 30-40ms. It was VERY obvious, even to the point of being clearly audible between the local string noise and the sound. You do learn to adjust to the sound not being exactly when you pluck the string and, ultimately, end up playing everything slightly earlier. However, the adjustment isn’t entirely comfortable.
Incidentally, the advice for this situation is to wear good headphones and to not monitor locally, but monitor the delayed sound.
And I think this is the point: it’s not that you can obviously hear a difference, but that there’s something about the feel that’s not the same.
I think there’s also a psychological thing where our brains are tuned for, and used to, the speed of sound and, combined with the other acoustic affects, anticipate the latency if we know where the real amp is. Delay sensitivity is also a very important part of our hearing, along with other acoustic effects, and influences our ability to locate sounds.
When we wear headphones, there’s a different acoustic environment to using an amp in a room: the speakers are right next to your ears (often in the ear canal) and there’s no room ambience.
I think it’s interesting that Boss, with their Waza Air headphones, seems to have successfully created a capability where they’ve transformed a headphone experience into something that has more of the feel of an amp in a room. I suspect they’ve used some ambisonic techniques to achieve this, which use, amongst other methods, tiny variations in the delay of the signal to change our perception of the location of the sound source.
Cheers,
Keith