Here's the link: http://www.whitecrowflutes.com/duets2.htm
The diagram on Barry's website is one more way to look at the pairing of flute keys when preparing play a Native American Flute duet in harmony with another flute player. In musical terms, the the "3rd harmony" and the "5th harmony" are the most pleasing to the ear (at least in western musical theory). A "3rd harmony" is actually 3 half steps/semitones (i.e. adjacent keys on the piano) from the primary note. A "5th harmony" is actually 7 half steps/semitones from the primary note. The 5th harmony is also known as the "perfect fifth".
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