People play live faster because of the adrenalin, you’so excited to play they you automatically play faster.

This is HAW we came up with the tempo in the bands I played in.

Someone comes up with a riff or a lick and it already has a tempo in their hand which sounds good. The rest of the band builds the rest of the song around this part with the same speed.

Sometimes we go down to half speed for some part just for the effect. Sometimes we make the song faster at the end for the effect to make it more brutal.

There are occasions that someone in the band feels that the song is too fast or too slow after we already wrote it. In this case we try the new tempo, if everyone is feeling it’s better we switch to that new tempi.

I honestly can’t say with 100% certainty but I can speak to my experience with playing in an ensemble. For small sets, think a duet like violin and piano, usually there is an agreed upon “lead” and the other player(s) match them. In larger ensembles, band or orchestra, the conductor is god so we should be following them for tempo and queues. That being said, we listen to each other for certain queues and phrases to know when to join in. Generally we match whatever percussion or bass is doing, because that’s usually where time is kept.

I don’t think you can codify it more than “they do it by gut.” I think it’s pretty rare that a song goes unaltered from the spark in somebody’s head to mastered recording without many changes. It’s a collaborative effort that involves the producers and friends as well.

I think the more somebody is knowledgeable in musical theory, can read and write notes, and maybe even has perfect pitch, the more fully formed an idea will be when it gets to the early stages of recording. But musicians are not all Mozarts.

I dabbled in making electronic music for a while as a hobby. There was only me, I don’t remember anything from musical theory class in school, can barely read notation - in short: I’m not even mediocre. But even I felt occasionally that I needed to speed a track up or down. It’s a gut feeling.

I know from a drummer friend of mine that performing live is hard. You’re either very good at keeping time, like, you have an unshakable metronome in your head, or the tempo naturally speeds up. That’s why during production a lot of musicians get the metronome via a click track in their ears to make sure they don’t deviate too far from what BPM they wanted to hit. During live concerts I think a lot of drummers, as the metronomes of the band, get a click track in their ears as well. And there may be concerts where a song is sped up compared to the recording on purpose, but is still played with a click track because it sounds better live when it’s faster, maybe because it’s missing a lot of stuff from the production that filled gaps at the lower speed. So you can say everything has a tendency to speed up live but sometimes tracks that are performed faster are an artistic choice.

Every performance is different. Sometimes it’s faster sometimes it’s slower. Some times it changes during the song.

Some of that is responding to the audience’s energy or whatever, and some of it is just the natural human imprecision.

For your typical rock band set up, the drummer sets the tempo, which is part of why they slap their sticks together at the start of a song. (They may also do it because they think it’s cool.) sometimes different people might set the tempo, but the drums picks it up and carries it.

Jazz is a bit more fluid, especially with improvisational jazz, where everyone takes a turn leading and with slight changes. More rigid jazz, it‘s set by the leader with everyone coming together on that- but also, jazz is a bit more fluid and responsive to the audience. L