I still don’t think companies serve you ads based on spying through your microphone

https://simonwillison.net/2023/Dec/14/ai-trust-crisis/#facebook-dont-spy-microphone

Mobile phone operating systems don’t allow apps to invisibly access the microphone.

Except if they are system apps. Which is the case with many, many manufacturer ROMs, and even stock Android has non-open-source system apps.

Privacy researchers can audit communications between devices and Facebook to confirm if this is happening.

Also between other apps, Google apps, voice assistants etc.? Because most data is just sold and bought. It's much easier to let google process this and then buy the finished data. Also makes the next point much more centralized and cost-effective:

Running high quality voice recognition like this at scale is extremely expensive—I had a conversation with a friend who works on server-based machine learning at Apple a few years ago who found the entire idea laughable.

Facebook say they aren’t doing this. The risk to their reputation if they are caught in a lie is astronomical.

Ted said he wouldn't murder people. The risk to his reputation if he would be cought in a lie is astronomical.

As with many conspiracy theories, too many people would have to be “in the loop” and not blow the whistle.

Have few people involved, tell fewer the actual purpose, and have them all sign a general NDA. And the people that do speak are reprimanded to be a conspiracy theorist.

Facebook don’t need to do this: there are much, much cheaper and more effective ways to target ads at you than spying through your microphone. These methods have been working incredibly well for years.

Like buying the data, still collected through voice, from google or other advertisers.