Listen to this octave. It is tuned to a "pure" 4:2/"pure" 6:3 where the difference between the test intervals is less than 3%, the threshold of human beat perception.

You will hear:
1) A3A4 unfiltered
2) A3A4 filtered around the 4:2 partial (A5)
3) A3A4 filtered around the 6:3 partial (E6)

4) The M3 F3A3 filtered around A5
5) The M10 F3A4 filtered around A5
The speed of 4) and 5) measures the size of the 4:2. If they beat the same speed, as these do, it is a pure 4:2. (But remember, the human ear isn't perfect. This is actually a wide 4:2)

6) The m3 A3C4 filtered around E6
7) The M6 C4A4 filtered around E6
The speed of 6) and 7) measures the size of the 6:3. If they beat the same speed, as these do, it is a pure 6:3. (But remember, the human ear isn't perfect. This is actually a wide 6:3)

8) And then the A3A4 again, unfiltered.

свернуть