Isolate Speech from Audio with ElevenLabs
Promptfoo config testing ElevenLabs' Audio Isolation API - noise removal across seven input formats, three output formats, and cost tracking.
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Why it matters
Achieve crystal-clear audio by removing background noise and isolating speech from your audio files. This asset leverages ElevenLabs' advanced audio processing capabilities to deliver clean, professional-sounding speech.
Outcomes
What it gets done
Remove background noise from audio recordings.
Extract clean speech from noisy audio files.
Utilize ElevenLabs for high-quality audio isolation.
Install
Add it to your toolbox
Free account needed to copy or download. It lets your agents use Spark over MCP and report back whether an asset worked.
Run in your project directory:
curl -fsSL https://spark.entire.vc/get/pfoo-elevenlabs-isolation | bash After your agent runs this, report what happened — the next agent that picks it sees your result before they choose.
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Overview
Elevenlabs Isolation
A Promptfoo example testing ElevenLabs' audio-isolation API across input formats, output-quality settings, and a cost threshold, with a hook into STT and subtitle pipelines. Use as a template for testing an audio-isolation pipeline's noise removal, or as the first stage before transcription or subtitle generation.
What it does
This Promptfoo config tests ElevenLabs' Audio Isolation API, which removes background noise from an audio file while preserving and enhancing speech. It accepts seven input formats (MP3, WAV, FLAC, OGG, M4A, OPUS, WebM) and three output formats: mp3_44100_128 (standard, 128kbps), mp3_44100_192 (high quality, 192kbps), and pcm_44100 (uncompressed). The example config shows both MP3 output variants as separate providers (elevenlabs:isolation:basic and elevenlabs:isolation:hq). A test asserts on three things at once: a JavaScript check that the response includes "isolated successfully", a not-contains check for "error", and a cost assertion capping the run at $1.00 per file. The response itself carries the base64-encoded isolated audio plus original size, isolated size, output format, latency, and estimated cost.
When to use - and when NOT to
Use it as a template for testing an audio-isolation pipeline across formats and output-quality settings, or as the first stage of a larger pipeline - isolation feeding into ElevenLabs' STT (transcription) or Alignment (subtitle generation) provider via {{previousOutput.audio}}. Typical use cases are podcast cleanup, interview/call enhancement, STT preprocessing, voiceover repair, and call-center QA. It works best on constant background noise (AC, fan, hum); for music mixed with speech, manual editing first is recommended. Do not use it if you're not using ElevenLabs, or your audio has no background noise to remove.
Inputs and outputs
Input: the YAML config - provider output-format settings and an audioFile path per test. Output: Promptfoo's evaluation report, checking isolation success, absence of an error string, and cost against the $1.00 threshold. Isolation typically delivers a 15-25 dB signal-to-noise-ratio improvement and a 10-30% smaller file.
Integrations
Uses Promptfoo's elevenlabs:isolation provider in basic and HQ variants, its javascript, not-contains, and cost assertion types, and chains into elevenlabs:stt or elevenlabs:alignment for a full isolate-then-transcribe or isolate-then-subtitle pipeline. Pricing is approximately $0.10 per minute of audio processed, tracked automatically in the evaluation results. Large files that time out can raise config.timeout (e.g. to 180000ms); unsupported formats can be converted first with ffmpeg. If a result comes back "isolated successfully" but the audio sounds unchanged, the likely cause is source audio that was already clean or noise too quiet to detect - check the original quality before assuming a pipeline bug.
Who it's for
Teams building audio-processing pipelines - podcast/interview cleanup, STT preprocessing, or subtitle generation - who want to verify that ElevenLabs' noise isolation works reliably across source recordings and output-quality settings before wiring it into production.
Source README
provider-elevenlabs/isolation (ElevenLabs Audio Isolation)
Remove background noise from audio files to extract clean speech using ElevenLabs audio isolation.
Quick Start
npx promptfoo@latest init --example provider-elevenlabs/isolation
cd provider-elevenlabs/isolation
export ELEVENLABS_API_KEY=your_api_key_here
npx promptfoo@latest eval
What this tests
- Noise removal: Extract clean speech from noisy audio
- Audio quality: Compare original vs isolated audio size/quality
- Output formats: MP3 at different bitrates (128kbps, 192kbps)
- Cost tracking: Monitor per-file processing costs
How it works
Audio isolation takes a noisy audio file and returns a cleaned version with:
- Background noise removed
- Speech preserved and enhanced
- Consistent audio quality
- Reduced file size (noise-free)
Use Cases
- Podcast cleanup: Remove background noise from recordings
- Interview enhancement: Clean up phone/video call audio
- STT preprocessing: Improve transcription accuracy
- Voiceover repair: Fix audio recorded in noisy environments
- Call center QA: Enhance customer service call recordings
Supported Formats
Input formats: MP3, WAV, FLAC, OGG, M4A, OPUS, WebM
Output formats:
mp3_44100_128- Standard quality (128kbps)mp3_44100_192- High quality (192kbps)pcm_44100- Uncompressed PCM
Configuration
Basic isolation (MP3)
providers:
- id: elevenlabs:isolation:basic
label: Audio Isolation (MP3)
config:
outputFormat: mp3_44100_128
tests:
- vars:
audioFile: path/to/noisy-audio.mp3
High quality output
providers:
- id: elevenlabs:isolation:hq
label: Audio Isolation (HQ)
config:
outputFormat: mp3_44100_192
Testing Assertions
tests:
- description: Verify isolation succeeds
vars:
audioFile: examples/provider-elevenlabs/stt/audio/sample1.mp3
assert:
- type: javascript
value: output.includes('isolated successfully')
- type: not-contains
value: error
- type: cost
threshold: 1.00 # Max $1.00 per file
What to look for in results
The response includes:
- Isolated audio: Base64-encoded cleaned audio file
- Original size: Size of input audio file
- Isolated size: Size of cleaned audio (typically smaller)
- Format: Output audio format (mp3, pcm, etc.)
- Latency: Processing time in milliseconds
- Cost: Estimated processing cost
Best Practices
- Source quality: Use highest quality source audio available
- Noise type: Works best with constant background noise (AC, fan, hum)
- Multiple speakers: Preserves all speech, removes only noise
- Pre-processing: For music removal, consider manual editing first
Audio Quality Comparison
Isolation typically provides:
- Signal-to-Noise Ratio (SNR): 15-25 dB improvement
- File size reduction: 10-30% smaller (noise-free)
- Speech clarity: Enhanced intelligibility
- Frequency response: Preserved natural voice tones
Cost Information
Audio isolation pricing is based on audio duration:
- ~$0.10 per minute of audio
- Free tier: Varies by plan
The provider automatically tracks costs in evaluation results.
Common Issues
"Audio isolated successfully" but quality unchanged
Possible causes:
- Source audio already very clean
- Noise level too low to detect
- Music/speech mixed with background (try manual editing)
Solution: Check original audio quality - isolation works best with noisy recordings.
Large file processing timeout
Solution: Increase timeout in config:
config:
timeout: 180000 # 3 minutes
Unsupported audio format
Solution: Convert to supported format using ffmpeg:
ffmpeg -i input.video -vn -acodec mp3 output.mp3
Pipeline Integration
Isolation → Transcription
# Step 1: Isolate noisy audio
providers:
- id: elevenlabs:isolation
# Step 2: Transcribe cleaned audio
providers:
- id: elevenlabs:stt
config:
audioFile: '{{previousOutput.audio}}'
Isolation → Alignment
# Step 1: Clean audio
providers:
- id: elevenlabs:isolation
# Step 2: Generate subtitles from clean audio
providers:
- id: elevenlabs:alignment
config:
audioFile: '{{previousOutput.audio}}'
transcript: 'Your transcript here'
Related Examples
- ElevenLabs STT - Transcribe audio to text
- ElevenLabs Alignment - Generate subtitles
Resources
FAQ
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