user: Question: what is the value of the audio with a just ratio 21:20
Columns: ['interval name', 'size (steps)', 'size (cents)', 'just ratio', 'just (cents)', 'error', 'audio']
Types: ['text', 'real', 'real', 'text', 'real', 'text', 'text']
Sample row: ['perfect fifth', 9.0, 720.0, '3:2', 701.96, '+18.04', 'Play Category:Articles with hAudio microformats']
SQL:

assistant: SELECT "audio" FROM "Table" WHERE "just ratio" = '21:20';