[twinkletwinkle]

Not sure about Android phones with "Ok Google" but on iOS, all of Siri's voice processing is on the device. As opposed to Amazon Alexa which sends the data to the cloud for processing.

[millstone]

Siri does speech recognition on Apple’s servers, but commands are performed on the device. The server doesn’t know who you are.

[merinowool]

Is there an independent audit that can prove that?

[jadedhacker]

If they have your voice, they can identify you regardless of metadata can't they?

[ryanwaggoner]

I don't think this is true. I think they upload the audio to the cloud to process, but it's not linked to your user ID, only to the device ID.