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2nd Opinion

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Free desktop app that checks audiobook files against Audible/ACX technical specs — peak, RMS, sample rate, and head/tail silence.

Best for: Self-narrating authors and narrators who want a free pre-submission technical spec check on Mac, Windows, or Linux

Free
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Verified July 2026
21/25Audiobook ProductionVisit Website

Details

Service Type
Proofing Qc
Narration Type
Human, Ai
Distribution Channels
free· 12 categoriestechnical-qcacx· 2 categoriesaudible· 3 categoriesdesktop-app· 2 categoriesrmspeak-levelopen-tool

2nd Opinion, by narrator and developer Steven Jay Cohen, is a free cross-platform desktop app that scans finished audiobook files against Audible's direct-ingestion technical specs (stricter than ACX's) so you catch spec violations before you submit. Version 7.0.1 shipped in July 2025 and the tool is actively maintained.

  • Best for: Self-narrating authors and narrators who want a free, repeatable technical QC pass before uploading to Audible or ACX
  • Key features: Checks peak level (default ≤ -3.0 dB), average RMS (-18 to -23 dB), consistent channel count and sample rate (44.1k default), head silence (½–¾ sec), tail silence (2½–5 sec), and retail-sample length; thresholds are customizable
  • Platforms: macOS (Apple Silicon and Intel), Windows, and Linux
  • Pricing: Completely free; the developer accepts optional donations
  • Limitation: Technical audio analysis only — it does not check manuscript accuracy or narration performance, so pair it with a human proof-listener for content errors
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