The full article title is:
Big Brother: Mass Migration Forces Sweden Police to Install Hundreds of No Go Zone Microphones to Detect Crime
So, there is a problem with migrants in Sweden. Where do you draw the line which protects privacy yet provides police protection???
http://www.breitbart.com/london/2017/11/17/sweden-place-hundreds-microphones-no-go-zones-detect-crimes/
Quote from the article:
Authorities also made a note to mention that the system would not be used to record private conservations of individuals and that all the recordings would not be saved.
Note that the actual phrasing allows SOME of the recordings to be saved...
This is a slippery slope and absolutely needs careful monitoring by third parties. Once such a system is in place, it is far to easy to use for full monitoring of everything. Orwell's book: 1984 is the prototype...
Without trying to sound alarmist or instill panic, we have many aspects of this already being implemented across THIS country (the US). Europe is also following this trend.
I do call this a warning flag which should figure in your own "threat analysis".