Split tone

[2] Split tones can sound similar to a technique called growling, in which additional noise is produced from the throat while playing.

Liza Lim makes extensive use of split tones in Ehwaz for trumpet and percussion.

"[4] In a blog post for his Cologne-based ensemble musikFabrik, American trombonist Bruce Collings provided a basic method for producing split tones: In my experience, the best way to execute a split tone is to aim for the upper note, push the lower jaw a bit forwards and purse the lips a little more than normal.

[6] David Hickman writes "In most cases, double buzzes occur because of sore or bruised lips.

This causes the player to tilt the mouthpiece unconsciously at an abnormal angle to relieve pressure on the sore area.