Bassoon Crook
The S-shaped metal tube connecting the bassoon's mouthpiece (reed) to the body of the instrument.
What it means
The crook, also called the bocal, is the thin, S-curved metal tube on the bassoon that sits between the double reed and the top end of the instrument's wooden body. Its curved shape lets the reed be brought into a comfortable position for the player without curving the body itself.
Bassoons are usually supplied with several crooks of slightly different lengths, which allow fine adjustment of the instrument's overall pitch.
Musical use
As a connecting part, the crook has no musical function of its own, but it substantially shapes the bassoon's tone color, response, and intonation, since the reed's vibration is transmitted through it into the instrument's air column.
It should be distinguished from the clarinet's barrel, which serves a comparable connecting function but is built straight rather than curved, and from the reed itself, which is fitted onto the crook and sets the tone in motion.
Performance practice
If your bassoon sounds consistently too sharp or too flat, switching to a longer or shorter crook can help adjust the overall pitch before you address reed choice or embouchure. Handle the crook carefully, since it is thin-walled and easily bent.