Phase in audio is the timing of a waveform's positive and negative values in relationship to the amplitude of frequencies. In music production, this can have many implications on the elements in a song, sound effect, or any audio.
It is one thing that can either make or break a good mix and can even lead to more work later on when you EQ if you want to try and fix phasing issues.
The reason it can lead to more work - or ruin something if nothing is done - is due to certain frequencies being either boosted or reduced due to the timing of each track’s waveform at any given moment.
Since the phase of a waveform consists of positive and negative frequency values, these can lead to phase cancellation when they are not lined up.
Phase cancellation occurs when the values of two similar waves are opposite, known as being "out of phase".
For example, if you took a sine wave and looked at a reflection of it, one wave would go up in value while the other would go down. If they both started at the same time, it would be perfectly out of phase.
But, that's less likely than the subtle cancellation that can happen when it involves something like vocals and a guitar at a very similar pitch or delay in when they start, like when using multiple mics that may pick up both elements.
What this does is it will either make both sound weaker or thinner, but can completely cancel each other out if they are identical waveforms.
Fixing phasing issues is critical to be done right from the start of your mixing process.
First, you’ll want to identify if there is a phasing issue, you can do this by taking two or more elements in your mix and completely separating the signal by panning it to the far left and right.
Then bring it down to mono. If you noticed the frequencies become thin or less powerful, you may have found an issue with the phase of the elements you are comparing.
Knowing what polarity is will greatly help you fix phasing issues and also in understanding what phase is in the first place.
A quick tip is to try reversing the polarity of a waveform and listening for a change in the frequencies of the entire song. Stick with the value that fills the frequency spectrum more.
Updated: Apr 01, 2020
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