Jun Senoue and Kenichi Tokoi on Sonic Adventure Original Sound Track:
Heartless Colleague …for Boss: E-Series Targets
Senoue: There are also boss battles of fellow robots and I tried to decide on the more minimal feeling with artificialities than other music of boss battles. I think that a unique waviness appears.
Tokoi: With whammy bar, the guitar’s unique lowered pitch of the chord of every four bars is nicely reflected in the background with minimal feeling.