Researchers devised a new keyboard acoustic eavesdropping attack based on Voice-over-IP (VoIP) VoIP software is able to eavesdrop acoustic emanations of pressed keystrokes and transmits them to the interlocutors involved in the VoIP call. Attack is possible because each brand of keyboards emis distinct sounds, such as the various letters on the same keyboard. Attackers can reconstruct the victims input with an accuracy of 91.7% when it is known the target typing style.”]
Source: https://securityaffairs.co/wordpress/52493/breaking-news/skype-calls.html