A musical tuning is said to **distinguish** between two intervals in just intonation if the closest match to the two just intervals are two distinct intervals in the tuning. When a tuning fails to distinguish between two intervals, the difference between the just intervals is said to be tempered out.

31-ET tends to distinguish between far more intervals than 12-ET, but there are still some intervals involving the harmonics up through 11 that it fails to distinguish between.