> Recording and interpreting speech would require a lot of CPU (if done on device) or network bandwidth
I'm skeptical regarding bandwidth.
Modern codecs can achieve spectacular compression, you don't necessarily need to record audio-cd-level quality audio, and Facebook has state of the art hardware and software in terms of ai/ml and a very well trained workforce in the field.
If anything, one should regard Facebook as "capable of pulling this off".
That's assuming the audio gets uploaded. For the purposes of serving more relevant ads, simple hotword detection need only be good enough to distinguish eg Nike vs Adidas, and could be done locally. That changes the upload to mere bytes, which is way more easily obfuscated in any number of opaque IDs. fbclid= anyone?
I'm skeptical regarding bandwidth.
Modern codecs can achieve spectacular compression, you don't necessarily need to record audio-cd-level quality audio, and Facebook has state of the art hardware and software in terms of ai/ml and a very well trained workforce in the field.
If anything, one should regard Facebook as "capable of pulling this off".