It's true. Your devices are listening to you - Hacker News
Perspectives on what this claim might actually mean in practice
To me it's pretty clearly the same targeted advertising available anywhere with the extra claim of using "voice data". It doesn't say what the voice data is or where it comes from. They could say that when people do google searches using Siri/OkGoogle/the microphone option on Google - it's information they would use in an anonymized way to target ads, or rather Google does on your behalf, and it's technically a derivative of voice data.
I'm skeptical this is what people might think it is. To be clear, I think most readers would interpret this as "your phone is surreptiously listening to you via your microphone." If that were true, then there would be telltale signs of resource draw. Handling rich audio data has practical costs, whether battery, CPU, network, memory, and/or disk; that data has to be stored, transmitted, and processed somehow. I've never seen analysis that shows that's happening. Not to mention this capability is beyond what audio capture APIs in Android and iOS offer, as far as I know.