Psychoacoustics applied to production: we mix for a brain
How we perceive sound and how to use it when producing: louder seems better, masking, localisation, the precedence effect and the bass the brain reconstructs.
Hearing isn't a purely mechanical phenomenon. Sound reaches the ear as a pressure wave, but what we "hear" is what the brain does with that information. That's what psychoacoustics is about: how we perceive sound. For anyone producing and mixing, understanding it is a huge advantage, because we don't mix for a meter, we mix for a brain.
Why a song gets to you
Choosing a song to suit your mood isn't a purely mechanical process. When you put on a sad song, you often don't choose it for the lyrics but for the melody and the music around them: that's the part that resonates with you at a more physical level. The lyrics connect emotionally because they remind you of something personal. But if you heard the story without the music, you probably wouldn't play it on repeat. That's where psychoacoustics comes in: how all those factors combine so that perception turns a physical fact, the propagation of sound, into a response.
Five psychoacoustic ideas I use when producing
1. Louder seems better
Our sensitivity to lows and highs changes with volume (the equal-loudness contours). Turn it up and we hear more lows and highs, and the sound seems "better". That's why, when comparing two versions, an EQ on or off, or your track against a reference, you have to match loudness. It's also the root of the loudness war.
2. Masking
A loud sound can cover a quieter one at nearby frequencies. That's why a mid-heavy pad buries the vocal even when the pad isn't loud. The fix is usually sharing out the spectrum with EQ rather than raising levels.
3. How we localise sound
The brain uses tiny differences in level and timing between the two ears to tell where a sound comes from. We're fairly good at localising horizontally and much worse vertically. That's the basis of panning, stereo width, and why low frequencies, which are hard to localise, usually sit in the centre (see the stereo field).
4. The precedence effect
If the same sound arrives twice with a very short time difference, we perceive it as one, located in the direction of the first. That's what lets you widen with short delays… and what can cause phase problems if overused.
5. The missing bass
When a sound has clear harmonics, the brain can "reconstruct" its fundamental even if the speaker doesn't reproduce it. That's why an 808 with some saturation or upper harmonics can still be heard on a phone, which barely reproduces low end.
Expectation listens too
What we expect to hear shapes what we hear. If you know you've switched on an expensive plugin, it's easy to convince yourself it sounds better. When in doubt, compare blind and at matched loudness: it's the most honest way to decide.
Understanding how we hear doesn't replace a trained ear, but it helps you make better decisions at every stage of mixing and mastering.