Patent ID: 7504575

Claim:
An intonation training device comprising: a user interface including a key specifier which the user employs to specify a musical key and a switch which the user uses to switch the intonation training device between an active state and an inactive state; an audio output; and an audio signal producer that responds when the user employs the switch to switch the intonation training device into the active state by producing a sustained audio signal that is a pure chord, the pure chord including at least two simultaneously-sounded distinct pitches, one pitch being at an interval in a scale of the specified key relative to a fundamental pitch for the specified key and further having a ratio to the fundamental pitch for the specified key which is substantially a ratio of small integers and the other pitch belonging to a set of fundamental pitches for the specified musical key and providing the audio signal to the audio output, the audio signal producer remaining in the active state until the user again employs the switch to switch the intonation device into the inactive state, whereupon the audio signal producer responds by ceasing to produce the sustained audio signal.