Trumpets don’t need it much until you get into the top end of the range, where certain notes are out of pitch. 5th partial is particularly flat, and 7th is sharp. Using 3rd valve as a replacement for 1+2 is flat, so you use the slide to correct.
Doesn’t really matter until you get to a pretty high level, are playing in a large brass band or know your instrument well enough to know which notes tend to be a few hz off.
Weather can also be an exaggerating factor, so playing indoors won’t have the same need
It’s for tuning
Trumpets don’t need it much until you get into the top end of the range, where certain notes are out of pitch. 5th partial is particularly flat, and 7th is sharp. Using 3rd valve as a replacement for 1+2 is flat, so you use the slide to correct.
Doesn’t really matter until you get to a pretty high level, are playing in a large brass band or know your instrument well enough to know which notes tend to be a few hz off.
Weather can also be an exaggerating factor, so playing indoors won’t have the same need