Understanding frequency masking is crucial if you want to produce clear, defined mixes – but first, you have to understand why this issue is so important. For hand-on practice don't miss our EQ Ear-Training tools in the EQ Playground.
Imagine a man talking in a deep voice. Now imagine two more men with deep voices talking at the same time and at the same volume. It suddenly becomes much harder to understand what any of them are saying.
The same thing happens with musical elements in your mix – if different instruments are playing in the same frequency range, the mix can become cluttered and ill-defined. Below are some tips on how to fix this problem.
1. Consider Your Arrangement
OK, so technically this isn't fixing the problem at all – it is doing your best to avoid it in the first place. Is there any way you can avoid different instruments playing at the same pitch? Perhaps you can play the guitar part an octave higher to stop it from masking the upper bass notes, or maybe the piano chords can be played an octave lower to prevent them from clashing with the guitar.
You might also consider arranging your song so that instruments playing at the same pitch play at different times – for example you could write interlocking melodies so the horn section plays whenever the vocals drop out.
2. Think About Panning
Of course you won't always be able to arrange a track so that there is no masking. Panning won't fix the issue completely but it can improve it. If two instruments are playing at the same frequency then try to pan them away from each other. It's very common in mixes to have the rhythm guitar panned on the opposite side to the lead guitar, and this can make each of those parts much clearer.
3. Use Subtractive EQs
This is probably the most important of all of these tips. If two musical elements are competing for the same range of frequencies, you can unclutter the mix by removing those competing frequencies from one of them. For example, the higher frequencies of a bass guitar can mask the lower frequencies of a rhythm guitar.
You can clear up masking issues by subtracting the low end of the rhythm guitar or the upper reaches of the bass. When using subtractive EQs to fix masking, you need to consider which musical part is the most important in your mix. If a piano and a vocal are competing, then the vocal is probably the more important element. You should therefore concentrate your use of subtractive EQ on the piano, so that the vocal retains more of its character.
4. Use High and Low Pass Filtering
An easy way to de-clutter a mix is to remove unnecessary frequencies from some of your instruments. You can declutter the bottom end of a mix by using a high pass filter on your guitars and synths – leaving that area of the mix clear for bass and drums. Or you can, for example, cut your guitars above 10kHz, leaving them less likely to mask some of the higher frequency vocal details in your mix.