[mrhottakes]

The trumpet, french horn, tuba, and euphonium also rely on the tuning slide to control pitch, so that's not an accurate statement.

[mbrameld]

Do you mainly control pitch with the tuning slide or the valves on those instruments? I think you mainly control pitch with the valves and only supplement with a tuning slide for certain notes, depending on the instrument, and therefore the statement is accurate.

[analog31]

Mainly the valves. The tuning slides help with a number of things, including the fact that the harmonics (notes above the first ocatave) are not precisely in tune with the fundamentals. A trumpet typically has a trigger lever or a loop for your finger on one or two of the tuning slides.

You use it as needed. If you're playing a really fast passage, you'll likely skip it, but shorter notes are harder to place the precise pitch anyway.

If you really want to see tuning slides in action, find a video of a good tuba soloist.

[jeffbee]

The slides are needed, at least on the trumpet, because the tuning is perfect when using one valve but it's way off when you use two at once.

[jeffbee]

Indeed, a trumpet has one slide for tuning only and two more slides that are used while playing, so it's not even technically correct.

[bluGill]

Your trumpet maybe, but my trumpet from 1957 only has tuning slides, which cannot be used while playing.

[jeffbee]

Interesting. A student horn I guess? I've never owned one that didn't have at least a third valve slide ring. I think they were widespread around the time that the trumpet really took over from the cornet, around 1900-1920. My pre-War Olds has moving slides.

[bluGill]

I know a few cases where slides were added later. I don't know when they became common but impression is layer.

[Polizeiposaune]

Yep. A basic trumpet has more slides than a basic trombone.