Display the degree of correlation at the adobe premiere audio peak metering

Let's start by understanding the term phase correlation and how we typically show it in our meters.

Mostly, phase correlation is used to determine the mono compatibility of a stereo signal, but depending on where you use it, it can also reveal other things, such as bad microphone placement.

The term phase correlation refers to the phase relationship between two sources, and with a phase correlation meter, you get a simple view of the changing phase relationship between those two sources.

There are three main ways two sources can relate - and anywhere in between.

• Identical: They are 100% identical
• Unrelated: They don't relate at all and have nothing in common
• Switched Polarity: They are identical, but one of the signals has its phase inverted

In a phase correlation meter, these three stages are normally described on a linear scale going from -1 (switched polarity) over 0 (unrelated) to 1 (identical). The numbers -1, 0 and 1 are not randomly chosen as they are the cosine of the angle of degrees of the phase difference between the two sources.

Phase relations below 0 are shown in red and relations above 0 are shown in green.

If left and right channels are identical, there are zero degrees of phase difference between them, and since the cosine of 0 degrees is 1, that's what the meter will tell you.

If left and right are different, unrelated signals, the phase correlation between them will be 90 degrees and the cosine of 90 degrees is 0.

And if left and right are the same, but right is inverted, the phase difference would be 180 degrees, and the meter will show -1, which is the cosine of 180 degrees.

Normal stereo mixes usually show correlation values between 0.3 and 0.7.

Many thanks in advance
Andreas