Answer: Sound on a brass instrument comes from a vibrating column of air inside the instrument. The player makes this column of air vibrate by buzzing the lips while blowing air through a cup or funnel shaped mouthpiece. The mouthpiece connects to a length of brass tubing ending in a bell.
Explanation: its called InTeRnEt!???!?!??!?!?!?!?!!?!?!?!??!??!!
