About Frequencies in Music

Today I want to talk about a topic that is baffling to a lot of musicians – so baffling that many don’t even get why they might *want* to understand it. And that is: audio frequencies.

Now already we’re sounding quite dry and scientific! And audio frequencies are basically a science-y view on music, and all sound. But that actually proves to be fascinating and quite powerful for a musician – once you get your head around it.

This is one of those topics that is far too huge for a short podcast episode to really cover. We could literally do a hundred episodes about audio frequencies and music. So I’m going to focus here just on the fundamental “what and why” of learning about frequencies – and leave all of the “how” for now. But I will mention at the end a great free resource you can check out if you want to dive in.

Why frequencies are important

So let’s begin with: why talk about audio frequencies at all on the musicality podcast? Well, the first thing to say is that “audio” is just another word for “sound”. All music is experienced as sound, and audio *frequencies* are a particular way of analysing, representing and understanding what’s going on in sound.

You might have come across frequencies in your musical life in a few places. We mentioned it in our previous episode on Tone when talking about bass and treble, low frequencies and high frequencies. It came up in our interviews with Jeremy Fisher and Allan Hubert Wright talking about how the human voice can do some interesting and unexpected things – and we can explain what’s going on by looking at the frequencies. You might have seen the big mixer desk in a studio or at a live gig where there are various sliders to control different frequencies. Or if you’re an electronic musician or you’ve done some home recording you’ve probably played around with equaliser settings or plugin controls that are set in terms of frequencies.

In my experience a lot of musicians bump up against this idea of frequencies and often figure out how to do what they need to with the equipment they’re using or wherever it’s come up. But most don’t take the time to really look into this topic – which is a shame because there’s a lot of exciting stuff that can be empowering to you as a musician. More on that later.

Learning about Frequencies

When I first learned about frequencies it was in the context of a high school science class, talking about waves in water, or a spring or string bouncing and vibrating, or some really abstract stuff about how light works. And I was a geeky kid so that stuff was interesting to me. And I kind of got that sound was about air vibrating and that was a pressure wave and it vibrated at a certain frequency. But I don’t think it was until I got to university and studied physics and computer science and got into the nitty gritty of frequency domain transformations and fast Fourier Transforms and a bunch of other stuff with intimidating names that I really *got* why frequency was so important for thinking about sound. And then when I did my masters we really went deep into music specifically and this scientific view on what’s happening in a musical sound.

Actually, that’s a lie. I did catch glimpses of why this stuff was cool earlier on. I remember spending lots of time fiddling with the EQ settings in Winamp to make my music sound better, and looking at the cool visualisations my computer could show based on the frequencies in the music – and I kind of got the idea that there were a *lot* of frequencies in music. It wasn’t just that a sound wave had one frequency which was how fast it vibrates the air. There was some way of looking at music that made it *all about* frequencies.

So then at university I learned all the cool underlying maths and science and I was lucky to do one of the only masters programs in the world that focused on, essentially, the science and data of music.

All that is to say: I am definitely biased! I love this stuff. But I definitely remember how baffling it used to be, and I’m happy to say that you definitely do *not* need to go as deep as all that for frequencies to be fascinating and useful to you as a musician.

What is a Frequency?

Okay. So what is a frequency? Well, it’s the rate at which something happens. A low frequency means it’s happening once in a while, a high frequency means it’s happening very very often. And in the case of sound we’re talking about how often the air moves back and forwards in a wave. That back-and-forward motion hits our ear and we perceive it as sound. We measure that rate in a unit called Hertz, where 1 Hertz means once per second, 2 Hertz means twice per second, and so on.

Humans can hear air vibrating at roughly 20 Hertz up to 20,000 Hertz – it differs from person to person and with age, but that’s a good rule of thumb to remember.

Now here’s where it gets interesting. We perceive low frequencies as a low *pitch* and high frequencies as a *high* pitch. The relationship between pitch and frequency is a bit subtle – we might do a future episode all about that. But as a starting point you can think of the range from low to high frequency as mapping to how we hear from low pitch up to high pitch.

So let’s hear an example, the simplest possible example: Here is a sound which actually does have just one frequency, like that science class explanation of how sound works. You might have actually heard of this one, it’s called “A 440” because it’s 440 Hertz and the pitch is the note we call “A”.

And here’s 262 Hertz, which is the pitch we call “Middle C”.

When a sound wave has just one frequency like this it’s called a “sine wave” – something you might have come across in maths class. And this pretty much never happens in real life. It’s great as a demonstration and a tool for thinking about sound, but real sounds, and especially musical sounds always have a mixture of frequencies in them, like you’ve taken a bunch of those simple sine waves at different frequencies, some higher, some lower, and combined them.

For example if I add a few more frequencies into this sound – essentially taking several of these simple sine waves and playing them at the same time, you might hear this.

Now that’s starting to sound a bit more musical! With a fade in and out, it actually sounds a bit like a note played on an oboe

So every musical sound you actually hear in real life, from a single note on oboe (which actually sounds a bit like a sine wave) through to every drum and cymbal in the percussion section is made up of a mix of frequencies.

On the percussion end, the sound becomes what’s called “noise” – basically what happens when you throw not just a few frequencies in there, but *all* frequencies.

That’s called white noise – and noise is more interesting than you might think – another topic for another episode…

So all sounds exist somewhere on that range, from a single frequency through to the noise of all frequencies at once.

Now that we’ve had a taste of audio frequencies and how they might relate to music I’m going to hit pause – and we’ll pick this up in a Part Two to talk about the two big reasons frequencies are important for musicians and why you might want to learn a lot more about them.

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