What Google puts in AI audio
SynthID for audio hides the watermark in the sound itself, so it can’t be heard and doesn’t live in the file’s tags. Google uses it on music from Lyria and on NotebookLM’s Audio Overviews. When an audio file does carry C2PA Content Credentials, this checker reads and verifies them in MP3, WAV and M4A files, and says who they name and whether their signer is on the C2PA trust list. It also scans the file’s XMP and tags for the IPTC label trainedAlgorithmicMedia and for Google’s “Made with Google AI” wording.
Checking the watermark itself
Upload the file to Gemini and ask “Was this audio created or edited by Google AI?”. Gemini accepts one file under an hour and up to 100 MB. It only recognises Google’s watermark: for ChatGPT voice or OpenAI API audio, OpenAI’s Verify tool, a public preview, takes MP3, WAV, AAC, FLAC, OGG, Opus and PCM files. It checks C2PA and SynthID in images, and SynthID in audio. OpenAI has added SynthID to its audio since 31 July 2026.
Reading the result for audio
A marker here is a statement in the file: signed and verifiable for C2PA, unsigned for IPTC labels and tags. No markers is the usual result for audio, because most players, editors and platforms don’t write or keep provenance data, and that tells you nothing about the watermark. A voice clip that matters, for example one used in a scam call or a news story, is worth checking in both Gemini and the tool of whichever company is suspected of making it.
For any other file, use the SynthID checker.
Sources
- Gemini Apps Help: Verify AI-generated images, videos, and audio, read 26 September 2026
- Google: image verification in the Gemini app, C2PA in Nano Banana Pro images, November 2025
- Google: video verification in the Gemini app (up to 100 MB and 90 seconds), 18 December 2025
- Google: SynthID checks in Search (rolling out to Chrome), C2PA checks in Gemini, AI Content Detection API, 19 May 2026
- Google: SynthID Detector portal and waitlist, 20 May 2025
- Google DeepMind: SynthID, read 26 September 2026
- Google Cloud: Content Credentials on generated images and videos, updated 25 September 2026
- Google: C2PA in the Pixel 10 camera and Google Photos, 10 September 2025
- IPTC: Google AI transparency based on IPTC standards, 28 October 2024
- IPTC NewsCodes: Digital Source Type vocabulary, modified 26 September 2024
- OpenAI: SynthID in ChatGPT, Codex and API images (audio added 31 July 2026), 19 May 2026
- OpenAI: Verify OpenAI-generated content (public preview), read 26 September 2026