We’re all just trying to get the best mix we can, but sometimes it can be hard to tell whether we’re making things better or worse. Or even more disheartening; making a change one day and then playing at a friend’s or client’s and it sounding nothing like you expected.

There are as many ways to approach a mix as there are mixers, but once it’s bounced it doesn’t matter if you used the analog modelling plug-in or the modern, transparent one. As long as it serves the song and sound better for it, who cares? Since every song is different advice can only be so specific, we often fall back on the maxim “trust you ears”.

But how can we trust our ears if they tell us one thing one day, and something different the next? The first step might be the simplest; tame your listening volume.

Not all sounds are created equal

Studies have shown that the ear is non-linear in it’s response. This means that a mid heavy sound will appear louder than a signal of equal power that is mostly lows or highs. More than that, the difference in perceived volume will change based on how loud the signal itself is. What does this mean for mixing? Good question. First, let me introduce you to Fletcher and Munson.

These two guys did a series of experiments where the participants were played two pure tones; a 1kHz test signal and one at another frequency. The subject then changed the volume of the second signal until they perceived it was the same volume. For some frequencies the signal needed a mich higher absolute volume.

What they found has been condensed into what we call Equal Loudness Contours, the most well known being the Fletcher-Munson Curve. It describes how my ears behave, how your ears behave and how your listener’s ears will behave. Armed with this knowledge we can predict the effects of our listening volume and take steps to avoid problems down the line.

Sorry if you’ve seen this diagram before, but there’s useful information in this graph. Along the bottom we’ve got the frequency, and along the side we’ve got the power. The lines show the actual output needed to sound to feel like it’s the same volume as the 1kHz test tone. The further from the bottom the louder the test sound needs to be.

Simply put, we suck at hearing low frequencies and anything above 5kHz is a bit screwy too. And as the volume gets louder, looking at the higher up lines, something else happens. At higher volumes the curve changes shape and becomes flatter. Meaning that turning up the volume in the mids will have a fairly regular, predictable effect, but turning up the bass… The bass will still sound quiet at higher volumes and then suddenly get a lot louder quickly.

What does this mean for my mix?

The good news is that this is a shared response between us all. We can reverse engineer this graph into a good rule of thumb:

Good sounding mixes mixed at low volumes will sound good at high volumes, but with a bit more bass. Good sounding mixes mixed at high volume may sound thin and lacking bass at low volumes. The fix is simple; do 90% of your mixing at low volumes, only going loud to double check, but not to fine tune. A good volume I’ve heard suggested is the volume you’d have background music; loud enough to hear, but quiet enough to talk over without raising your voice

You can also keep this in mind when playing with individual effects. Any time an effect changes the volume of the source A/B the effect at the same perceived level as the input and make your changes before setting the output level. For example, listen to how your compressor sounds before taking up that headroom you just created. Don’t rely on your meters for this.

If you keep your volumes low and consistent the next time you reach for the controls you’ll be one step closer to hearing just the song and not your ears. And as an added bonus your ears will fatigue less quickly, meaning you can mix longer at a stretch.

I’ve had mixes suffer because of this in the past myself. A band mate once complained that my bass was lacking when he was checking mixes on his headphones. He suggested that it was my speakers bass response, and I think he was half right. Looking back, I may just have been monitoring too hot and turned down the bass when I should have turned down the whole mix.

Don’t forget to listen to other material at these volumes too, to learn what they sound like in the same environment you’re mixing in. I’ve wilfully neglected acoustic treatment here because the same rule applies if you’re using headphones. No listening environment is perfect, but you’re using the same ears in every situation.