The Wonderful World of Mix Perception
Written by Chris McCormack

Welcome to the world of what I like to term mix perception. So what is mix perception? In a nutshell, what goes into your ears before affects what you perceive after. Sounds obvious right? It’s actually very subtle and very easily missed in today’s hectic climate!

This can be broken down further into two aspects of the same thing. Call them macroperception and microperception if you will.

Firstly, there is what you are exposed to in your environment as a separate event or series of events before you go into the studio. This is macroperception and it comes in two flavours: The one where a constant noise (such as driving on the motorway with the window down) actually physically impairs certain frequencies in your hearing for a period afterwards, making accurate mix decisions impossible. That’s not particularly relevant in the context of this article. We all know going clubbing leaves you deaf for days afterwards, it’s not too scientific!

Of much more relevance is the subtle phenomenon of your hearing being exposed to a large balance shift. Take for example watching a chat show on your portable television complete with a 1 inch speaker for an hour before going straight into the studio to continue working on that vocal take on your full range monitors. After a short while the TV sounds “normal”, but suddenly in the studio, the voice sounds hugely overblown. You can suddenly hear so much 100 Hz-250 Hz it can’t be right! You might mistakenly start hacking frequencies out of it thinking “that’s much better”, only 5 minutes later to be putting them all back again.

Now think about this in terms of what goes on within the actual confines of your track. It’s like a self contained version of the above example. Say you have a sound within the mix, and every time you hear it you’re not happy. It sounds reedy and thin but when you add in more bass it sounds somehow overblown and frankly, worse. Is it the sound that is causing the problem, or is it actually a sound which chimed in 5 seconds before which shifts your perception? Where do you draw the correct balance here?

This is something I have been aware of myself for many years and perhaps one of the reasons I think I’m a pretty good mastering engineer is because I have learnt to constantly adjust my hearing for different situations and hone in on what I feel is the correct balance instinctively.

If you listen to much of the output from the 80’s pop era for instance, it’s almost hilariously lacking any real bass extension compared to a lot of modern music (think “Take On Me” by A-ha or much of the Fine Young Cannibals output), a lot of it is super bright in balance compared to modern music, and yet it sounds great.

If you listen to a lot of modern home produced independent music, it’s much heavier in balance and has no real *true* clarity in the top, and yet it too sounds great. That’s pretty interesting right? What’s the deal here?

It’s all about sounds in context and the spectral balance.

If you were to suddenly play one of these 80’s tunes after an hour of the modern stuff, it might quite literally cut your ears to shreds. You might say the mix was terrible in fact. And the same applies vice versa. Suddenly the modern stuff sounds like the tweeters have blown, or your ears are full of wax. And yet on different days you might say both mixes are great. Why is that?

When mixing, ultimately what you are looking to achieve is a context for all the sounds to exist within. So if you are making a mellow chilled out tune, let’s just say a filtered pad of some sort through a long reverb with some associated lofi-ish sounds, simply putting a big dry saw tooth wave through an exciter and cranking the top end in an attempt to give the track a feeling of clarity is going to sound seriously harsh, unlistenable and completely out of context. Yet that very same treatment on the 80’s track may in fact be necessary in order for it to sound correct. Remember that on different days you might still say “both mixes sound great!”

One of the things I am trying to get to here is that ultimately, it doesn’t matter if say your kick drum is not the biggest in the world, as long as the bass line that goes with it is also similarly restrained. So why not cut some of the bass out of the bassline using a high pass, and listen to your kick in context again, it has more depth without you having done a thing to it right? There is a perfect example of adjusting the balance of one sound to affect the perception of another. It’s what great mixes are all about. It’s microperception no less.

Things like ultimate bass extension, depth, super soaring clarity and air are wonderful things to be able to engineer into a mix, whether it is by the mix itself or with mastering, but none of this *really* matters if the sounds themselves don’t exist together within the context of the spectral playing field of the track. Listen to ‘Being Boiled’ by the Human League (I seem to be very 80’s today, hehe). By any standards the sound is “weak”, but it’s great to listen to because within the confines of the ultimate bottom and top frequency ceilings (which are pretty limited), all the sounds fit together in context and therefore the mix and the sound are ultimately really satisfying.

There is a lot of room for our ears to adjust to differing spectral balances, what we don’t adjust to is sounds that are out of context with other sounds. A sound in the mix which is too bright compared to the other sounds will always be too bright. It will never be right. Yet a bright mix with the same bright sound has the potential to sound great.

This is where I guess I can make a link to mastering, because a well balanced mix in sound element terms makes me happy. It doesn’t matter if it’s a bit dull, a bit bass light, a bit lacking in mids. What matters is when I bring out more top, ALL the sounds in the region come out together as one. When I add in bass, ALL the notes step forward together. I can really DO things with mixes like these. The result can be a beautiful thing. At this point I am normally thanked profusely, but without the contextual sound balance within the mix for me to work with, the job of spectrally optimizing, shaping and balancing a track for a truly satisfying sound becomes that much more difficult.

As usual, best of luck! As always I am happy to give advice, so don’t be afraid to get in touch.