Number of Players: 2 Instrumentation: Trombone and Vibraphone Number of mallets: 4 Difficulty: Intermediate Edge was written for trombonist Joshua Hauser and percussionist Eric Willie. The outer movements feature spirited interplay between the instruments, and the middle movement is a lyrical duet. The piece explores many coloristic devices, including vocal effects for the trombone and bowing and harmonics for the vibraphone.