Brass Instruments: Introduction
Brass instruments are named for the material that they are made of. What sets brass instruments apart from woodwind instruments are the removable mouthpieces (usually made of metal) that are required of each instrument. Sound on these instruments is made by placing a mouthpiece against the lips, and forcing air through the lips which then causes them to vibrate. This vibration is called buzzing. All brass players must buzz their lips in order to produce a sound.
Just like the woodwinds, smaller instruments have smaller mouthpieces, and larger instruments have larger mouthpieces. Larger brass instruments produce lower sounds.