When air rushes through a corrugated tube, it can produce an audible tone. That’s the idea behind the branching corrugahorn. A single mouthpiece leads to an air chamber with several corrugated tubes extending from it. The player blows into the mouthpiece while stopping the tubes by covering the ends with fingertips. Whenever the player lifts a finger to open a tube, that tube will sound. By blowing harder or softer, the player makes the air go faster or slower to bring out different notes in each tube. Each tube can produce several notes, and between three or four of them they produce a complete scale.
In the audio clip, the branching corrugahorn is accompanied by alto clarinet, huaca, cooler guitar and an electric bass. A video of this instrument can be found among the demonstrations in this youtube playlist.