Aural Method for Proving Pure Unisons and Intervals

This method is very powerful but it won't work if you do not have a system that produces many pure intervals, like the Mark Cerisano Tuning System.

Many ETDs produce intervals that are close to pure but this system requires that the intervals are pure. It also requires that you can hear pure intervals.

The beauty of this is that many pure intervals sound like pure unisons when they are right. If you know what a pure unison sounds like, you can use this system.

The Key Principle

Intervals are made of unisons.
"If a unison is not pure, the interval can not be pure."
Think of it like adding shot glasses of water to make one big glass of water. If one shot glass is salt water, the large glass will taste like salt.
All the unisons in an interval must be pure if you want the interval to be pure.

What this means is that if you hear an interval is not pure, you KNOW it has to be for one of these two reasons:

1) One or both unisons are NOT pure

or

2) The interval is not pure

Before checking the interval, make sure the building blocks of the interval (the unisons) are not the problem. Check the unisons.

Then if the unisons ARE pure, you KNOW it's the interval.

Here is where Auditory Illusion is used against itself.

When first listening to the check intervals, you may have concluded they are the same speed because you weren't listening carefully enough, and you wanted to hear them the same.

After confirming that the interval is not pure but the unisons are, then you KNOW the check intervals are not the same.

Relisten and force your ear to choose which one is faster.

Pick a note to tweak up or down using DSU and feedback from the tests, and your interval will now be pure, but more importantly, your unisons will be confirmed pure.

This is called the Pure Unison / Pure Interval Procedure.