Michael Harney, experiencing his first day on a trombone (!), has the innovative correct-O-meter attached to the bell
of his horn.
A laser on the backside scans the music and flashes green (when the note is played correctly)
and red (when it is wrong).
The goal is to keep the light green all the time. If it flashes red during
a 16th note
there's not a heck
of a lot you can do about it!