The most consonant harmonies in the Bohlen Pierce scale (to my ear) are those that fall within the gamut of Harry Partch’s 7-limit just intonation system. The BP intervals 9/7 and 7/5 (steps 3 and 4) seem to be the most pleasing, and their equal temperament counterparts are less than 4 cents from just.
The step 2 interval 25/21 is 302 cents, an acceptable minor third to western ears, but equal temperament changes it to a flat-sounding 292 cents.
The step 12 interval 25/9 (B note) is totally outside of the western 12-tone system.
This chart shows the intersection between the Bohlen Pierce scale and the 7-limit just intonation system. The D and B notes suffer the problems mentioned above. The difference between cents and round hundreds is a rough indicator of how alien the interval will sound compared to traditional western harmony.
| steps | name | ratio | cents | cents ET | 12-tone name |
|---|---|---|---|---|---|
| 0 | C | 1/1 | 0 | 0 | Unison |
| 2 | D | 25/21 | 302 | 293 | Minor 3rd |
| 3 | E | 9/7 | 439 | 435 | none |
| 4 | F | 7/5 | 582 | 585 | Tritone |
| 6 | G | 5/3 | 884 | 877 | Major 6th |
| 7 | H | 9/5 | 1018 | 1024 | Minor 7th |
| 9 | J | 15/7 | 1319 | 1316 | Dim 9th |
| 10 | A | 7/3 | 1467 | 1463 | Aug 9th |
| 12 | B | 25/9 | 1769 | 1755 | none |
| 13 | C | 3/1 | 1902 | 1902 | 12th |