Cymatics vs Spectrogram
サイマティクス / スペクトログラム
Both sit in Diagrammatic Expression, so the question is not what they belong to but how they behave. Both are read here as technique. They are reached for with some of the same intent, which is where they get confused.
Cymatics
The experiment of seeing sound as a pattern in matter, beginning with the Chladni figures that sand draws on a vibrating plate. Each frequency brings out its own geometry, which makes this the oldest device for witnessing how sound and form correspond.
Spectrogram
![Spectrogram — 母音 [i][u][a] のスペクトログラム — Wikimedia Commons / CC BY 2.0](https://commons.wikimedia.org/wiki/File:Spectrogram%20-iua-.png)
A visualization that maps sound onto a plane of time, frequency and intensity. From birdsong research to the DAW screen it became the standard way to see the shape of a sound, and artists have since taken to hiding pictures inside it.
| Cymatics | Spectrogram | |
|---|---|---|
| Era | 1787– | 1940s– |
| Family | Diagrammatic Expression | Diagrammatic Expression |
| Kind | Technique | Technique |
| Cues | Chladni figures / Standing waves in sand and powder / A pattern for every frequency / The directness of the apparatus | The time-frequency plane / Intensity as shading / Voiceprint patterns / Hidden-image play |
| Best used for | Building an exhibit of sound where the apparatus is part of the show · Letting people grasp the link between frequency and form by experience | Locating noise or overtones in a recording by eye instead of ear · Explaining how a sound changes as a single figure along time |
| Type | Fine dry powder, spread as a single thin layer on the plate | A log frequency axis, scale and units printed inside the figure |
| Composition | Center the clamped point, view from where symmetry appears | Time across and frequency up, an intensity key alongside |
| Material | An even metal plate or membrane, raking light to raise pattern | A colormap rising monotonically in lightness, never rainbow |
| Caution | Sweeping the frequency for a good looking video never lets a figure settle, and the central claim about sound and form fails to land. | Drawing without choosing a window length skews the tradeoff between time and frequency resolution, and artifacts get read as real features. |