FOAM: Physical Modeling Synth
Bubble & foam acoustics
$1.99 · Designed for iPad. Not verified for macOS.
iPad
A unique physically modeled synth built from the acoustics of bubbles and foam. Play it by touch, with MPE and multichannel support. Launch price of $2 until September 12
FOAM is an attempt at opening new territory in synthesis.
Very few fundamentally new synthesis methods have emerged in the past twenty years — FM, granular, wavetable, physical modeling of struck and bowed things — the paradigms were mostly set by the early 90s. FOAM models something almost no instrument has: the acoustics of bubbles and foam.
Bubble acoustics is one of the most sonically rich phenomena in nature and one of the least explored in synthesis. The sound of a wave receding isn't five or ten things — it is thousands of simultaneous bubble interactions whose aggregate creates the texture. FOAM implements that physics directly. Not samples: actual acoustic modeling of what happens when gas meets liquid, from the initial film rupture through cavity resonance to viscous damping.
HOW IT WORKS
Each bubble is a physics equation, not a recording or a grain. FOAM models 11+ distinct acoustic stages of a bubble's life — membrane rupture, resonance, collapse, decay — and every parameter feeds the formulas live. Turn up viscosity and small bubbles die fast while large ones ring longer in the thicker liquid, as they do in nature.
PLAY BY TOUCH
The iPad edition adds a full-screen touch surface — a tonal pad layout you play directly with your fingers, octave shift built in. Full MPE: per-note pitch bend, slide and pressure map to bubble size, pitch sweep, ring time, emission rate and amplitude.
THE ENGINE
Dense foam is rendered by many voices across multiple CPU cores. A configurable CPU governor sets the ceiling for voice density — open it up on a fast iPad, or dial it back in a busy AUM session. The transition from discrete pops to continuous foam emerges naturally from the sheer number of independent interactions.
RANGE
From single droplets to dense rafts. From water to honey to mercury. From delicate rain to walls of noise — with fantasy-sized bubbles that can dip into sub-bass if you find them.
PARAMETERS
- Bubble Physics: rate, size, ring, cascade
- Realism: shimmer, natural balance, jets, mirror depth
- Texture: stereo width, magic (psychoacoustic intensity)
- Liquid Identity: 10 materials — water, seawater, glycerol, honey, mercury and more — plus manual mass, tension, viscosity
- Foam Topology: coarsening, collapse, wetness, aging
- Modulation: chaos, drift, scatter, with per-knob locking
- Surge: temporal envelope shapes
Also runs as an Audio Unit (AUv3) inside AUM, Cubasis, GarageBand and other iPad hosts.
Ratings & Reviews
The developer, Polytope K.K., indicated that the app’s privacy practices may include handling of data as described below. For more information, see the developer’s privacy policy .
Data Not Collected
The developer does not collect any data from this app.
Accessibility
The developer has not yet indicated which accessibility features this app supports. Learn More
Information
- Seller
- Polytope K.K.
- Size
- 20.5 MB
- Category
- Music
- Compatibility
Requires iPadOS 15.0 or later.
- iPad
Requires iPadOS 15.0 or later. - Mac
Requires macOS 12.0 or later and a Mac with Apple M1 chip or later. - Apple Vision
Requires visionOS 1.0 or later.
- iPad
- Age Rating
4+
- 4+
- Copyright
- © 2026 Polytope K.K.
