[1]https://www.newsbreakapp.com/n/0MbloCip?s=a3&pd=02h1yVjC

Hackers can tell what people are typing just by listening through a smartphone's
 microphone

Daily Mail




Hackers could be able to tell what you are typing on your computer just by liste
ning to your keystrokes through your smartphone's microphone, a new study warns.

Shared from News Break


   Jim Bell's comment:

   Peter Wright's 1970's book, Spycatcher, described an early, primitive
   version of this technology.

References

   1. https://www.newsbreakapp.com/n/0MbloCip?s=a3&pd=02h1yVjC