Musical rhythm, is taught using a sequenced rhythm pattern, wherein a user's strike within a time window around each note maintains suppression of audible output. If a strike falls outside the time window, output resumes. FIG. 2 shows a smartphone/tablet app. Pad 13 is struck in harmony with a rhythmic pattern on display 1. Means 3 to 11 adjust app parameters. Means 2 control rhythm. A display preferably shows current and past states of the system during a session (e.g. metronome suppressed, metronome non-suppressed, strike detected in time window, strikes outside time window), as well as time remaining in the current session, as either a ‘clock’ or ‘pie chart’ type, or rectilinear ‘bar’ type, the ‘time remaining’ segment of the display being progressively replaced by sections e.g. of differing colour or texture corresponding to the current state, with the ‘time past’ segments displaying the past states.