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Audio Visualization

Is a picture worth a thousand words in audio? The value of thinking about -- and looking at -- the mix in a graphical way.

By Andy Coules June 13, 2018

It is said that “a picture is worth a thousand words” and nowhere is this more applicable than when trying to teach complex concepts.

A graphical depiction can often convey an idea better, and quicker, than a whole bunch of words. This is because our brains are mainly image processors, not word processors; the part of our brain that processes words is actually very small in comparison to the part that processes visual information.

Therefore visual cues help us to better store and retrieve complex information.

Bearing this in mind I’ve been exploring various ways of representing key audio concepts and terminology visually. This invariably involves a certain degree of simplification but I think the results are a useful weapon in the battle against incomprehension.

Let’s start by looking at a simple way to represent the frequency content of a single sound, such as a kick drum, shown here against a vertical axis denoting frequency (Figure 1).

On the left is a representation of a kick drum that has been miked in a standard way, with a single microphone poking through the hole in the front skin.

Here we can see there is slightly more energy in the bottom and top of the sound (i.e., the thud and the click) than there is in the middle – quite common when close miking a kick drum.

The right side of the image represents the same signal after a little EQ has been applied, in this instance the bottom end has been enhanced while the lower and upper mid range frequencies have been reduced slightly to give that classic kick drum sound.

EQ isn’t the only way we affect the frequency content of sounds so let’s take a look at some other methods (Figure 2).

On the left is a representation of a snare drum that has been miked up in standard manner – a single mic above the top skin. In the middle is the same snare with a high-pass filter applied, as indicated by the fade (which denotes the gradual reduction in the lower frequency content). On the right is the same snare after compression has been applied. In this instance the compressor is limiting not just the dynamic range of the snare (which is difficult to depict in a static image) but also it’s frequency content, resulting in a tighter and punchier sound at the possible expense of some of the finer detail.

Now that we’ve established a simple way to visually represent the different sounds, and the ways in which we can affect them, let’s take a look at a full drum kit. The kit as a whole has the widest frequency range of just about any instrument (with the possible exception of the pipe organ), from the low thud of the kick drum to the fizzy sparkle of the cymbals.

It comprises multiple elements that all need to be miked up in a way that enables us to treat each individual sound in relative isolation such that when they are combined, they complement each and work together as a whole. If we take a standard four-piece drum kit, miked up in a standard way (i.e., a single mic on each drum with a pair of overheard mics), and just bring up all the faders, it might “look” something like Figure 3.


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About Andy

Andy Coules
Andy Coules

Sound Engineer, Tour Manager, Audio Educator
   
Andy Coules is a sound engineer and audio educator who has toured the world with a diverse array of acts in a wide range of genres.
http://andycoules.co.uk

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