denoise

Denoise audio

Reduce background noise in a speech recording.

Before invoking — sanity check

If the goal is transcription, denoising is usually not necessary. POC at https://github.com/danielrosehill/Crying-Baby-Audio-Scrub showed Whisper handles moderate background noise (e.g. baby crying) without preprocessing — the cleaned and uncleaned transcripts differed by only 5–6 word choices over 119 seconds.

Reach for this skill when:

• Severe noise is degrading even-for-humans intelligibility (wind, heavy traffic, music)
• Audio is destined for human listening rather than ASR
• ASR was tried on the raw audio and produced an unusable transcript

For mild/moderate noise prepping for transcription, skip this skill — go directly to preprocess-for-transcription and then transcribe.

Provider selection

Read ~/.config/claude-transcription/config.json for denoise_provider and prefer_local. If config missing, default to Auphonic (cheapest cloud option).

User may override per-invocation: "denoise with elevenlabs", "use deepfilternet", "local denoise".

Providers

Cloud (default)

Auphonic (default — ~$0.15/hr equivalent)

• API: https://auphonic.com/api/
• POST to /simple/productions.json with input_file, preset, or direct algorithm flags (denoise=true)
• Requires AUPHONIC_API_KEY
• Docs: https://auphonic.com/help/api/

ElevenLabs Voice Isolator

• API: https://api.elevenlabs.io/v1/audio-isolation
• Requires ELEVENLABS_API_KEY

Dolby.io Media Enhance

• API: https://api.dolby.com/media/enhance
• Requires DOLBY_API_KEY and an input URL (upload to Dolby temp storage first)
• Expensive (~$0.50/min) — avoid unless user explicitly requests

Local

DeepFilterNet (ML, CPU-efficient)

• Install: uv tool install deepfilternet or pipx install deepfilternet
• Run: deepFilter <input.wav> -o <output.wav>
• Works fine on CPU; AMD GPU support via ONNX Runtime ROCm is experimental and usually not worth the setup.

ffmpeg afftdn (non-ML, instant)

• ffmpeg -i input.wav -af afftdn=nf=-25 output.wav
• Lower quality but zero dependencies and immediate.

Output convention

Write to <source_stem>.denoised.<ext> in the same directory as source, unless user specifies a path.

Error handling

• If API key env var missing → report which var and which provider, suggest running /configure.
• If ffmpeg missing → tell user to install it.
• If cloud API returns error → report status + body, don't silently fall back.