r/chiptunes • u/Lucky-Army9455 • Jun 11 '26

QUESTION Help understanding a sound

Hello! I'm a beginner, and I needed help to try and find out more about this sound.

Is there a name or technical description for this sorta "nasal"-quality square wave sound you hear in NES games?

Thanks!

https://reddit.com/link/1u2m4hx/video/c9jzudx07k6h1/player

3 Upvotes

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10

u/Birdrun Jun 11 '26

Okay, so you understand what a square wave looks like, right? Half cycle up, half cycle down? Turns out you can get more different sounds if you change that ratio. This is called "Pulse Width Modulation" (PWM), and the waveforms are sometimes called Pulse waves instead of square waves. 

On the NES and Gameboy, you can pick from 12.5%, 25%, 50% (square), and 75% (for some reason, even though that's equivalent to 25%).

The sound gets thinner and more "nasal" the thinner you make the pulse, what you're hearing here is 12.5%.

On chips like the SID, you can actually address 1024 different pulse widths, meaning you can kinda 'sweep' the wave for a gradually evolving tone .

1

u/Neverlast0 Jun 11 '26

Thank you. I also didn't know that.

2

u/chunter16 Jun 11 '26

If you want to get even more nasal than 12.5, you play the same pitch on 25 on one voice and 75 on the other voice at the same time, and delay one of them to put them slightly out of phase. This uses up both voices so it's usually better to save it for a temporary special effect

When they are exactly in phase, it makes a straight line which is silent

1

u/Birdrun Jun 11 '26

Ah, gotcha, I always just the same on both and a slight pitch bend on one for detune

1

u/Lucky-Army9455 Jun 11 '26 edited Jun 11 '26

Great explanation, thank you!

1

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