# Membrane Sound Lab

> Change a rectangular drum shape, strike point and pitch, then hear its modes. Explore a rectangular membrane with spatial mode plots, interactive strike positions and configurable synthesized WAV samples.

Part of usefulweb.app (https://usefulweb.app/). Part of [Tonegrid](https://tonegrid.usefulweb.app/) (ownerApp: tonegrid). Results are deterministic calculations from the inputs and the listed assumptions; the API returns exactly what the web page shows.

## Use it
- Human interface: https://tonegridmembranelab.usefulweb.app/ (interactive tool at https://tonegridmembranelab.usefulweb.app/tool)
- JSON API: POST https://tonegridmembranelab.usefulweb.app/api/v1/calculate with a JSON object of inputs (schema: https://tonegridmembranelab.usefulweb.app/api/v1/tool)
- OpenAPI: https://tonegridmembranelab.usefulweb.app/openapi.json
- MCP (Streamable HTTP): https://tonegridmembranelab.usefulweb.app/mcp - tool `tonegrid_membrane_lab`

## Inputs
- width (number): Relative width
- height (number): Relative height
- strikeX (number): Strike X (0–1)
- strikeY (number): Strike Y (0–1)
- pitch (number): Fundamental frequency (Hz)
- seconds (number): Sample duration (seconds)
- decay (number): Decay rate

## Method
- Fixed-edge rectangular membrane modes: frequency proportional to sqrt((m/width)^2+(n/height)^2). The first 24 modes from m,n=1..8 are shown with spatial phase plots.
- Strike weights and modeled exponential decay produce a mono 22.05 kHz WAV, with inaudible modes omitted and a short fade at both ends. No autoplay. This is a synthesis model, not arbitrary-shape FEM or material prediction.