Stem Stacker: hear a mix being built, layer by layer

Hearing a mix build up layer by layer

When you listen to a finished song you hear the result, not the decisions. Everything arrives at once and there's no way to tell what each element contributes, because you've never heard the same song without it. That's why plenty of people enjoy an excellent mix without being able to say one concrete thing about it.

Stem Stacker solves that with an Arkanoid mechanic: every block you break activates a stem and the song assembles in front of you. Drums alone first, then the bass comes in and suddenly there's weight, then the vocal and the mix finds its focus. That moment when one element enters and changes everything else is precisely what you need to learn to perceive.

The game part isn't ornament. Analytical listening is tiring: it demands sustained attention on something with no immediate reward, which is why almost nobody does the listening exercises books recommend. With a game mechanic, the game sustains the attention and the learning happens underneath — which is how most perceptual skills are acquired.

How to play, step by step

1.Pick a track. There are 15 songs and each comes split into the same four layers: Drums, Bass, Synth, Vocals.
2.The round starts with drums alone. That's the baseline, and it's worth listening for a couple of bars before breaking anything.
3.Break blocks with the paddle. Each row of blocks maps to a layer, and clearing a row activates that layer in the mix.
4.Listen to the moment each layer enters. That's the exercise: noticing what changes in everything else when the bass arrives, and again when the vocal does.
5.Completing the track leaves the full mix playing and unlocks that song's collectible vinyl.

What's in the catalogue

In-house productions — 7 tracks (5 free): Produced for this exercise, with the four layers separated so they're effortless to tell apart. They teach the format before the material gets complicated.
Artist Pool — 8 tracks (6 free): Real music by Maia San Miguel, Oh Margó, Monár, NVVP, Gillian Harwin, with their original stems. Here the layers aren't separated to teach but to sound good, which is considerably harder to hear.
The remaining 4 tracksPro: The last of each group require Pro. They're the denser mixes, where two layers share a range and a layer's entry registers not by volume but by what it takes away from the other.
Collectible vinyls: Every completed track unlocks its vinyl. It doesn't change the game; it exists to give a reason to come back to a listening exercise, which is exactly what people struggle to sustain.

How to get the learning, not just the game

When a layer enters, look away from the screen for a second. What changes is aural, and your eyes take the attention you need to notice it.
Ask what each layer took away, not just what it added. The bass adds weight and simultaneously masks part of the kick: that second half is what teaches mixing.
Replay a track you know with the full mix playing and try to separate the four layers mentally. It's the inverse exercise and the most useful one.
Try the same track on headphones and on a speaker. What vanishes on the second is exactly what you'd be building wrong in a mix of your own.

Frequently asked questions

What exactly is a stem?

One of the layers a mix is split into before it's summed: drums on one, bass on another, and so on. It isn't the same as a single track — a stem can group several — and it's the format studios exchange material in.

Do I need to be good at the game to learn anything?

No. The Arkanoid mechanic is there to sustain attention; if you're bad at it you simply take longer to assemble the mix and hear each entry for longer.

How many tracks can I play free?

11 of the 15, with no account, in the browser. 6 of those are Artist Pool tracks, so the real music isn't all behind the wall.

Do the artists get paid for this?

The Artist Pool tracks are by real independent artists and plays inside the game generate royalties for them. That's why the catalogue isn't library loops.

How is this different from Mix Space?

Here you activate layers and listen; in Mix Space you move those same layers around a three-dimensional space and make the decisions yourself. This is the listening exercise, that one is the mixing exercise.

Where to go next

If you then want to make the decisions on those same stems instead of just switching them on, that's Mix Space. And to know what each layer does as it joins the rest, the spectrum guide covers where each instrument lives and who it fights with. The specific case of the two layers that get in each other's way most is in kick and bass.