Personally, I was very sceptical of phones listening. But this paper on [1] "Ultrasonic Device Tracking", has convinced me that the technology is definitely possible.
Apparently it's known as ultrasonic malware and is a type of side-channel attack to leak information to/from devices. So high-frequency audio is transmitted to devices that are listening and can even respond.
The scary thing is that researchers have already found this type of software embedded into [2] many applications.
Now this isn't the same as listening to "human conversations", but it's not hard to believe that some apps are waiting for any audio and just sending it to servers somewhere...
What apps do you have installed on your phone? Any games? Apparently [3] some games listen to you, even in the background...
I wonder if anyone has made an implementation of this as a low-cost indoor positioning system for a smart home. Maybe with some simple beacons transmitting at a certain frequency, and the phone receiving, processing that and updating its estimated location to a home server. It probably wouldn't be precise enough for a definite location (and room-precision is usually enough), but coupled with other approaches...
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= The frequency range would probably have to be pet-safe, since dogs and cats can hear way higher frequencies that we can't.
Apparently it's known as ultrasonic malware and is a type of side-channel attack to leak information to/from devices. So high-frequency audio is transmitted to devices that are listening and can even respond.
The scary thing is that researchers have already found this type of software embedded into [2] many applications.
Now this isn't the same as listening to "human conversations", but it's not hard to believe that some apps are waiting for any audio and just sending it to servers somewhere...
What apps do you have installed on your phone? Any games? Apparently [3] some games listen to you, even in the background...
[1] https://intellisec.de/pubs/2016-batmobile.pdf
[2] https://www.bleepingcomputer.com/news/security/234-android-a...
[3] https://www.nytimes.com/2017/12/28/business/media/alphonso-a...