Waah!
And how did they manage in the olden days?

https://www.tiktok.com/@this.is.delacruz/video/7436992374242364715

https://www.tiktok.com/@this.is.delacruz/video/7432023946926591278

That latency in sound has always been a considered aspect on big concerts. Most of the effects (or artifacts) of the latency can be heard by ear as well. Earlier they might have calculated it themselves and set things so, or listened to the sound and adjusted by ear. The calculation is not that complicated, sound travels 1m per 3 milliseconds in the air, that is the latency. Every project you do, where latency can cause an artifact, you need to place or delay things according to that calculation. The only difference is that he is using the computer now instead of doing the calculation on his own. But you could do that as well: you measure the distance, calculate how much each speaker is late until the sound reaches you with the mathematical formula I mentioned, and then you set the knob yourself to that latency value that you calculated. To set it properly, they have some old well known schemes that is circulating in the sound engineering science for decades. They know in what situation you can expect the delays, which directions, which speakers. Sounds a bit complicated but actually it is not, and if you know the schemes, you set up things fast.

The other thing: you can see a lots of stuff in  front of that guy. In Digital era, the latency problem in electronic devices became more serious. So I have a suspicion that if you use less stuff like that in a concert, and those are analog, a part of the problem is already eliminated. I am not sure about this, but earlier artists had less problems with latency than in the era of comupters. For example if you had an old multitrack tape recorder and recorded something, that had unnoticeable latency, however if you buy a USB soundcard for windows, it can easily happen that you cannot record with it properly because of the huge latency, that you might not be able to eliminate, depending on the device you use. 

And just something interesting: if you are 100m from the stage, that is 300ms latency. It can happen in a big arena. While we are talking about milliseconds, 300 milliseconds of latency is easily detectable even by kids. If you transform that to TV: imagine you are watching a movie, and the sound comes that late, you will see the sound and moves are not it sync. The same happens in the arena: you see the singer singing, that the sound is coming well after they finished a sentence. Just to compare, for film, the allowed latency is 22 milliseconds.

That latency in sound has always been a considered aspect on big concerts. Most of the effects (or artifacts) of the latency can be heard by ear as well. Earlier they might have calculated it themselves and set things so, or listened to the sound and adjusted by ear. The calculation is not that complicated, sound travels 1m per 3 milliseconds in the air, that is the latency. Every project you do, where latency can cause an artifact, you need to place or delay things according to that calculation. The only difference is that he is using the computer now instead of doing the calculation on his own. But you could do that as well: you measure the distance, calculate how much each speaker is late until the sound reaches you with the mathematical formula I mentioned, and then you set the knob yourself to that latency value that you calculated. To set it properly, they have some old well known schemes that is circulating in the sound engineering science for decades. They know in what situation you can expect the delays, which directions, which speakers. Sounds a bit complicated but actually it is not, and if you know the schemes, you set up things fast.

The other thing: you can see a lots of stuff in  front of that guy. In Digital era, the latency problem in electronic devices became more serious. So I have a suspicion that if you use less stuff like that in a concert, and those are analog, a part of the problem is already eliminated. I am not sure about this, but earlier artists had less problems with latency than in the era of comupters. For example if you had an old multitrack tape recorder and recorded something, that had unnoticeable latency, however if you buy a USB soundcard for windows, it can easily happen that you cannot record with it properly because of the huge latency, that you might not be able to eliminate, depending on the device you use. 

And just something interesting: if you are 100m from the stage, that is 300ms latency. It can happen in a big arena. While we are talking about milliseconds, 300 milliseconds of latency is easily detectable even by kids. If you transform that to TV: imagine you are watching a movie, and the sound comes that late, you will see the sound and moves are not it sync. The same happens in the arena: you see the singer singing, that the sound is coming well after they finished a sentence. Just to compare, for film, the allowed latency is 22 milliseconds.

Wow this was a music and physical lesson great great explanation

Just one more interesting addition to this: there is a situation in connection with latency that might be the most important type of latency for you who are present in this forum and like making music. And that is the drum recording latency. This concert latency is a relative thing, depends on situations, there are people who don't even know about it but amplify small events. However drum latency affects all recording sessions. I have checked this once which mic placements are affected, I don't remember now clearly, but as I can recall the overhead microphones and the back microphone tend to get the sounds later than the others (no surprise, they are farther), and this has to be calculated into the process of recording drums. There are some basic schemes to solve this. Once we were recording drums, I had my description and followed that, but basically it is either about the mic placement or switching the phase button on or off on the channel of that specific mic to eliminate the artifact resulting from the drum latency. It is very minor, but causes an unpleasant effect, that sounds bad on the recording. So if you intend to record drums, you need to read about this. It is nothing complicated, but you need to remember and address the problem, else you will find the outcome strange.