UNISON - Two different pitches that have the same frequency. E.g., A equals 440 Hertz played on a flute and A equals 440 Hertz played on a clarinet. Two different pitches that have a 1:1 ratio.

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unison is instance of intervals
unison has 1:1 ratio
unison may be played by instruments
unison has specific sound
unison is two different pitches with 1:1 ratio
unison has two different pitches