The world of audio is an art form of very few rules. For many of us it was it's seemingly limitless boundaries that gained our initial attraction. However the one absolute that remains a constant is the mathematics behind the music. This math is connected to frequencies and understanding these frequencies can play a vital role to problem solving when it comes to your tracks.
MIXING IN A EMPTY ROOM
One of the biggest challenges while producing or mixing music is to avoid instruments from stepping on one another within the mix. The key is to allow everything to have it's own sonic space. Think of your mix like an empty room. Now think of each instrument or sound as a piece of carpet that will fit on the floor in that room. Each piece being of different shapes and colors. The goal is to fit all of the carpet pieces on the floor without putting them on top of each other. You also want to put colors that compliment one another next to each other. Now if you were doing this in a real room this task would be pretty easy as you could see the shape of each piece of carpet as well as the colors. In audio we can't see the shapes of sounds nor can we see colors to help guide us. But we have the next best thing in frequencies.
DO YOU HEAR WHAT I HEAR?
The human ear can hear from a frequency range of 20Hz to 20kHz. Some of us can pick up on sounds lower than 20Hz, but those are going to be mostly felt and not heard. As a matter of fact most of the sound from 20Hz to about 100Hz is going to be mostly felt my the average listener. Of course a lot depends on the age of the listener and many other factors, but for most the low end of the frequency scale is something we feel more than we actually hear. Understanding the math in frequencies is even more important when it comes to dealing with the low end of your track because for different reasons you may not be able to hear it. Poor monitors play a large part in the lack of hearing what's going on in the mix also.
STUCK IN THE MUD
Mud is a bad word when it comes to audio and one that you do not want to hear associated with your music. Unfortunately it is something you have to deal with sometimes when comes to music. Not just on the low end, but sometimes throughout the whole song. Mud is often the result of sounds clashing in the same frequency range. You can take care of this problem by taking out one of the offending sounds. But what if the sound is an important part to your song and taking it out is not an option. What do you do? This is where understanding the math behind the music can really help you out of a sticky situation.
THE QUICK FIX
So let's say your song has a french horn that plays an important part in the melody of the song so you don't want to just get rid of it. You also have a nice 808 kick drum that sounds great but they are clashing with each other. They are both taking up some of the same floor space in our room so we have to fix it. To help find where instruments are sitting in the mix by frequency I would recommend using a spectrum analyzer (a good one to use is Voxengo' SPAN, plus it is FREE) and a carnegie chart (here is nice interactive one I found HERE).
So after checking the note let's say the french horn is playing a C note 2nd octave. On our chart we can see that a C2 is 65Hz. Then we also see from our spectrum analyzer that our kick is peaking at 60Hz. Now with this information and an understanding that every frequency has a mathematical equivalent to it, our fix should be pretty easy. Since the french horn is part of the melody chances are our melody is in the key of “C” just at a high octave. You could move it to a different octave or a different note within the same chords of your song, but most likely your best bet would be to change your kick. Tuning your kick to play on a note that won't clash with your french horn would be your best way to handle the frequency clash and still maintain the notes to your song. To do this you would simply move the kick note in the piano section of your DAW to a note that doesn't cash but still gives you the kick sound that you want.
Article written by Alex Butler
Alex is an audio engineer, studio producer and freelance writer based out of Seattle, WA.