DeGoogle Yourself

This is also why a lot of the wake words are similar:

• Hey Siri
• Alexa / Echo
• OK Google / Hey Google

Those all have different vowel sounds, hard consonants etc. because without that there's not enough difference to make a unique wake word/phrase. Google needed something like "Hey" or "OK" before it because "Google" itself doesn't generate enough unique sounds to act as a keyword. They're also between 3 and 5 syllables because they need to be short enough to monitor for them, and long enough that they can be distinguished reliably from background noise.

The sounds are converted into MFCCs, which is sort-of an extremely lossy form of compression. It was originally used to identify numbers, like when someone would call into an automated switchboard and they'd have to say "one" or "five". It couldn't identify complex words, just distinguish between a small set of very different sounding numbers.

The way these systems work is that they're running on a very low-power loop converting ambient sounds into these patterns and seeing if there's a match for a wake-word pattern. The sound is converted into basically a time vs. frequency matrix and matched against the keyword / phrase. If there's a match it unlocks the much more computationally-expensive voice transcription programs, otherwise it just throws out the data.

You can tell that at least mobile devices aren't always listening because if they were actually doing full-on voice transcription all the time, the battery would drain much faster. If they were doing off-device voice transcription, the antenna would have to stay on a lot more, which would also kill the battery, and it would be visible in your bandwidth bill.

People need some more basic computer literacy. I get that the FAANG companies are "evil", and want to do unscrupulous things with your data, but there's often a simpler explanation that doesn't involve massive privacy violations that security researchers would have caught long ago.