# Aaron Gotwalt

> [Blog](/blog/) / [Projects](/projects/) / [Work](/work/) | [llms.txt](/llms.txt)

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## Deep Note

Date: 2025-07-09

The THX sound, rebuilt in a browser tab in about forty minutes.

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import DeepNote from "@components/DeepNote.astro";

<DeepNote />

You know the sound. The lights go down, a cloud of tones wanders around somewhere in the middle, and then it all swells and resolves into one enormous chord. That's the THX Deep Note, which James A. Moorer created at Lucasfilm and which debuted in 1983.

One evening in July 2025 I wanted to see if I could make it in a browser. The first commit and the last are about forty minutes apart, so this was not a serious undertaking. I built it with Claude, and the README is honest enough to call it vibe-coded.

It uses the Web Audio API to start 30 sawtooth oscillators at random pitches between 200 and 400 Hz. They sit there in a murky cluster for four seconds, then slide over three seconds onto a D major chord spread across five octaves, from D2 at 73 Hz up to A6 at 1,760 Hz. The slide is a simple cosine ease, so every voice leaves and arrives at the same time.

The one bit of actual thinking is equal-loudness compensation. Your ears are much less sensitive to bass than to the midrange, so each voice gets a gain boost based on where it's going to land, up to 3x for anything below 100 Hz. Without it, the bottom of the chord just disappears.

There's also a canvas chart that draws every voice's pitch as it plays, which is the part I actually find myself watching. Chaos on the left, order on the right.

The real Deep Note is a lot weirder than this, and a lot better. Turn your volume down before you press play anyway.