# Spectrogram (スペクトログラム)

> Sound mapped onto a plane of time, frequency and intensity. From birdsong research to the DAW screen, the standard way of seeing the shape of sound — complete with artists hiding pictures inside it.

- IndexStyle No.425 — https://indexstyle.org/styles/spectrogram
- Kind: Technique · Family: Diagrammatic Expression · Era: 1940s–
- Mood: Technology, Calm, Play
- Color cues: #e9e6dd / #67635d / #171615 (cues taken from reference works, not a fixed palette)

## Defining characteristics

- The time-frequency plane
- Intensity as shading
- Voiceprint patterns
- Hidden-image play

## Best used for

- Comparing primary sources and canonical works
- Extracting principles that transfer to other media

## Research method

This entry records a historical style; derive the treatment from its sources rather than a fixed recipe:

- Observe the letters, signs and scale of reference works
- Extract the one structure that governs gaze and information
- Verify the materials and behaviors specific to era, region and process

## What to avoid

Don't reduce it to surface signs. Verify the context of era, region, technology and makers.

## Application checklist

Before calling a piece an application of this style, check it against the defining characteristics:

- [ ] The time-frequency plane
- [ ] Intensity as shading
- [ ] Voiceprint patterns
- [ ] Hidden-image play
- [ ] At least one reference work below has been studied directly
- [ ] The caution above ("What to avoid") has been addressed

## Related styles

- **Cymatics (サイマティクス)** — Seeing sound as material pattern, beginning with Chladni's sand figures on vibrating plates: geometry appearing at each frequency — the oldest instrument for witnessing the correspondence of sound and form. → https://indexstyle.org/styles/cymatics
- **Photomicrography (顕微鏡写真)** — Scientific photography of structures too small to see. Bentley's snowflakes proved the scientific image beautiful — continued today in polarized color and fluorescence at Nikon Small World. → https://indexstyle.org/styles/photomicrography

## Further study

- Bell Labs voiceprint research
- ornithology's sonograms
- Aphex Twin's hidden faces

## Reference works

- 鳥のさえずりのスペクトログラム — https://commons.wikimedia.org/wiki/File:Hippolais%20polyglotta%20song%20spectrogram.png
- ソノグラム（CC BY-SA 4.0） — https://commons.wikimedia.org/wiki/File:Mindoro%20bleeding-heart%20song%20sonogram.png

## Source of record

- Cornell Lab — Macaulay Library — https://www.macaulaylibrary.org/

## Machine surfaces

- JSON: https://indexstyle.org/api/styles/spectrogram
- Image-generation prompt (legally clean): https://indexstyle.org/styles/spectrogram/prompt.txt
- MCP: https://indexstyle.org/mcp (tools: search_styles, get_style, compose_styles; prompts: image-prompt, apply-style)

## 日本語

音を時間×周波数×強度の面に写す可視化。鳥の声の研究からDTMの画面まで、「音の形」を見る標準となり、そこに絵を隠すアーティストまで現れた。

特徴: 時間×周波数の面／強度の濃淡／声紋のパターン／隠し絵の遊び
注意: 表面的な記号へ還元せず、時代・地域・技術・制作主体の文脈を確認する。