> ## Documentation Index
> Fetch the complete documentation index at: https://docs.nomn.jp/llms.txt
> Use this file to discover all available pages before exploring further.

# Bubble Physics

> How bubbles emerge, pop, ring, and fade

This is the heart of FOAM's sound generation. These controls determine the fundamental character of your bubble sounds.

## Primary Emission

| Knob     | What It Does                                                                                                                                                                                                                                  |
| -------- | --------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------- |
| **Rate** | How many bubbles are emitted per second. At minimum, you get sparse individual pops. At maximum, a dense foam cascade. Exponentially scaled — small movements at the low end create subtle changes, while the upper range gets dense quickly. |
| **Size** | The physical size of bubbles (0.1-50 mm radius), which directly determines pitch via the Minnaert resonance equation. Larger bubbles = lower pitch, smaller bubbles = higher pitch.                                                           |
| **Ring** | How long each bubble resonates after bursting (5-625 ms). Short times give crisp pops; longer times create sustained, bell-like tones. Default is 125 ms (physically realistic).                                                              |

## Cascade & Movement

| Knob        | What It Does                                                                                                                                                                        |
| ----------- | ----------------------------------------------------------------------------------------------------------------------------------------------------------------------------------- |
| **Cascade** | When a bubble bursts, it can spawn child bubbles. At 0, bubbles are independent. Higher values create chain reactions — foam avalanches where one pop triggers many.                |
| **Glide**   | Portamento between bubble sizes. At 0, each bubble has its exact size. Higher values smooth the transition, as if bubbles are expanding or contracting as they rise through liquid. |

## Realism Physics

| Knob                | What It Does                                                                                                                                                                                                    |
| ------------------- | --------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------- |
| **Shimmer**         | Real bubbles aren't perfect spheres — they wobble and deform. This adds subtle pitch modulation, creating organic "chorus-like" movement.                                                                       |
| **Natural Balance** | Controls the natural amplitude relationship between bubble sizes. At 100% (physics-accurate, the default), large bubbles are louder than small ones. At 0%, all bubbles have equal loudness regardless of size. |
| **Jets**            | When bubbles burst at the surface, they can produce secondary "plink" sounds. Adds the characteristic rain-drop-on-water quality.                                                                               |

## Flow Type

The **Flow Type** dropdown controls the statistical pattern and pitch behavior of bubble emission:

| Mode           | Character                                                                                   |
| -------------- | ------------------------------------------------------------------------------------------- |
| **Poisson**    | Random, natural timing — like champagne fizz                                                |
| **Nucleation** | Bubbles emerge in clusters from nucleation sites                                            |
| **Foam Raft**  | Dense, raft-like emission patterns                                                          |
| **Turbulent**  | Chaotic, swirling emission timing                                                           |
| **Melodic**    | Each MIDI note plays one tightly-pitched bubble — turns FOAM into a melodic instrument      |
| **Harmonic**   | Bubbles spread across the selected scale around the played note — chordal/harmonic textures |

<Tip>
  **Melodic** and **Harmonic** modes also activate pitch-tracking on the Resonator (in Fluid Dynamics) — the resonant body retunes itself to whichever note you're holding. Combine with the Cave or Cistern preset for tunable cinematic textures.
</Tip>