A trumpet mouthpiece extends effective pipe length, especially lower ones.

Evidence

The addition of a mouthpiece at the other end of the main bore also affects the frequency of some of the modes. The mouthpiece consists of a cup-shaped cavity that communicates via a small aperture with a short conical pipe. The mouthpiece has a resonant frequency associated with it, which is generally in the region of 850 Hz for a trumpet, which is otherwise known as the “popping frequency” since it can be heard by slapping its lip contact end on the flattened palm of one hand (Benade, 1976). The addition of a mouthpiece effectively extends the overall pipe length by an increasing amount. Benade notes that this effect “is a steady increase nearly to the top of the instrument’s playing range” and that a mouthpiece with a “lower popping frequency will show a greater total change in effective length as one goes up in frequency” (Benade, 1976, p. 416). — David M. Howard, Jamie Angus, Acoustics and Psychoacoustics, 1247

Categorization

• CANDY: The popping frequency test - slapping the mouthpiece on one’s palm - is a fun practical trick to try.
• DEFINE: Defines the mouthpiece’s popping frequency and its role in extending effective pipe length.