Phonon

Phonon is the speech recognition engine from Fermion Research. It runs the Phonon models on Apple silicon through MLX, on CPUs under Linux (x86-64 and Arm), Windows and macOS, and on NVIDIA GPUs through the CUDA image. It transcribes files from the command line, transcribes the microphone live, and serves an OpenAI-compatible endpoint. Phonon-2, a 164 MB download, is the current model, and Phonon-1 (415 MB), Phonon-1 Big (581 MB) and Phonon-1 Micro (285 MB) also run.

Models

Accuracy and speed for each model are on its model page (fermionresearch.com/models/phonon-2 and the model cards above).

Install

pip install fermion-research

Apple silicon (MLX engine)

pip install mlx mlx-audio mlx-lm soundfile scipy zstandard

Linux and Windows CPUs. On Linux, install torch from its CPU wheel index first, which skips the GPU build.

pip install --no-deps torch --index-url https://download.pytorch.org/whl/cpu   # Linux only
pip install fermion-research torch safetensors soundfile scipy zstandard

CPU container (amd64 and arm64)

docker run --rm -v "$PWD":/audio -v phonon-cache:/home/phonon/.cache ghcr.io/fermionresearch/phonon-cpu:2.0.3 transcribe phonon-2 /audio/recording.wav

NVIDIA CUDA container

docker run --rm --gpus all -v "$PWD":/audio -v phonon-cache:/home/phonon/.cache ghcr.io/fermionresearch/phonon-cuda:1.0.4 transcribe phonon-2 /audio/recording.wav

Run

phonon runs Phonon-2, phonon-1 runs Phonon-1, and fermion <command> <model> runs any model by name. Name the model. Phonon never guesses.

phonon transcribe meeting.wav               # transcribe a file with Phonon-2
phonon listen                               # live microphone transcription (Apple silicon)
phonon serve                                # OpenAI-compatible HTTP server on 127.0.0.1:8000
fermion transcribe phonon-2 meeting.wav     # the same, naming the model

curl -s http://127.0.0.1:8000/v1/audio/transcriptions \
  -F "file=@meeting.wav" \
  -F "model=phonon-2"

Dictation tools

A dictation tool keeps one Phonon server running and sends each recording to it, over a local port or an owner-only Unix socket.

fermion serve phonon-2 --port 8010 --threads 4         # or: phonon serve --port 8010
fermion serve phonon-2 --unix-socket ~/.cache/fermion/phonon.sock   # owner-only socket in place of an API key

engine = "whisper"
[whisper]
backend = "remote"
remote_endpoint = "http://127.0.0.1:8010"
remote_model = "phonon-2"

Keeping the server running at login is covered in docs/server.md.

fermion models lists every model with its aliases and marks the ones already on the machine.

Documentation

• docs/cli.md, the command line.
• docs/server.md, the HTTP server and its API.
• docs/install.md, installation on every platform.
• docs/cpu.md, running on CPUs, no GPU required.
• docs/cuda.md, the NVIDIA CUDA image.
• docs/troubleshooting.md, fixes for common problems.

The CUDA image is built from docker-phonon2/ and the CPU image from docker-cpu-phonon2/.

Licence

The Phonon-2 weights are released under CC-BY-4.0. They are a derivative of NVIDIA's parakeet-tdt-0.6b-v3, with the changes listed in the NOTICE file of the weights repository. The Phonon-1 family weights and the command line are released under Apache-2.0, and Phonon-1 is built on Qwen/Qwen3-ASR-0.6B, also under Apache-2.0. See LICENSE and NOTICE.