README.md

metadata

title: Second Ear
emoji: 👂
colorFrom: indigo
colorTo: gray
sdk: gradio
sdk_version: 6.23.1
app_file: app.py
python_version: '3.12'
short_description: Realtime mix ear that writes Ableton MCP plans
startup_duration_timeout: 30m
pinned: false

Second Ear

A realtime music production assistant. It listens to what you're making, tells you what's wrong in engineer's language, and hands your agent an executable Ableton Live plan to fix it.

Built by Apolithos Studios.

What it actually does

Hears. A rolling 8-second window of whatever your browser input is carrying. Seven-band balance, K-weighted loudness, crest factor, stereo correlation, sub-band phase, tempo and key — re-metered twice a second, each band drawn against the target window for the genre you picked.

Judges. A rule engine with genre profiles (dubstep, DnB, house, trap, pop, ambient, streaming master). It doesn't report numbers, it reports consequences: "crest factor 4.8 dB — the transients are gone", and then the move that fixes it. A CLAP model adds the semantic layer, so the report can say "gritty distorted reese bass, over-compressed drums" alongside the measurements.

Acts. Findings compile into a sequence of Ableton MCP calls — load_instrument_or_effect, get_device_parameters, set_device_parameter — that an agent with a local Ableton MCP server runs directly against your set.

The honest architecture

This Space cannot touch your Live set. Nothing hosted on someone else's machine can. So the work is split:

Second Ear (here)	ears and judgement — measures, diagnoses, writes the plan
Ableton MCP (your machine)	hands — executes the plan against the running set

Every endpoint here is an MCP tool, so one agent can hold both.

{
  "mcpServers": {
    "second-ear": {
      "command": "npx",
      "args": ["mcp-remote",
               "https://apolithosstudios-second-ear.hf.space/gradio_api/mcp/sse"]
    }
  }
}

Tool	Does
analyse_file	full report: measurements, findings, critique, Ableton plan
measure	raw metrics as JSON, no opinions
ableton_plan	just the Ableton MCP call sequence

Feeding it live audio

The Live tab hears your browser's input device. To point it at your master bus:

1. Install a loopback driver — BlackHole (free) or Loopback.
2. Route Live's output, or a dedicated send, to that device.
3. Select it when the browser asks for microphone permission.

Caveat worth stating plainly: browsers apply echo cancellation, noise suppression and auto gain to captured audio. That's fine for direction — the sub creeping up, the drop losing punch, the low mids filling in — and it is not fine for absolute numbers. For measurement-grade LUFS and true peak, bounce a file and use the Bounce tab. Live is the ear on your shoulder; Bounce is the meter.

Configuration

Variable	Effect
HF_TOKEN	(secret) enables the written critique via Inference Providers. Without it the rule engine runs alone and the UI says so.
EAR_LLM_MODEL	override the narration model (default Qwen/Qwen3-235B-A22B-Instruct-2507)

Measurement notes

• Loudness is ITU-R BS.1770-4: K-weighted, 400 ms blocks, absolute gate at -70 LUFS and a -10 LU relative gate.
• True peak is 4× oversampled.
• Everything resamples to 48 kHz on the way in, so the K-weighting biquads stay valid and metrics are comparable across sources.
• Band judgements fire on ratios between bands, not absolute fractions — absolute band energy drifts with arrangement density, ratios survive it.
• Key is Krumhansl-Schmuckler over an FFT chroma; tempo is autocorrelation of a spectral-flux onset envelope with octave correction. Both are estimates and the UI reports them as such.