A type of flute. Instruments whose pitch is produced by an air column moving through a channel, or duct, and directed to strike a sharp edge or lip causing the air column to split and vibrate. The upper end of the channel is blocked by a fipple which forces the air through the duct. Typically, duct flutes have fingerholes to change the length of the vibrating air column to change pitch, but can come in a single- pitch version or plunger version as in the slide whistle. Several types of duct flutes include recorder, flageolet, penny whistle, whistle flute and slide whistle.