It's the part of a wind instrument that's called an embouchure
The 
proper embouchure allows the instrumentalist to play the instrument at its full ... 
Other research notes that virtually all brass performers rely upon the upward... [DOC] [TLE] Mouthpiece (woodwind) - Wikipedia [PAR] The mouthpiece of a woodwind instrument is that part of the instrument which is 
placed partly in ... Its function is to provide an opening through which air enters 
the instrument and one end of an air chamber to be set into ...