Is your partner having an affair?

The database of Ashley Madison's adulterers that was exposed by hackers has some wondering whether their partner is faithful. 
How do you know? What are the signs?
Business Insider cites psychologists who've scrutinized various organizations including the FBI and the Los Angeles Police Department.
First and foremost, get an opinion from a friend as to whether your partner is straying.  Other people, even strangers, often can to detect when something isn't kosher with someone else's relationship.
Another idea: Listen to the sound of your partner's voice. Men with higher testosterone levels to have deeper voices, and women with more estrogen tend to have higher-pitched speech.
And as it turns out, higher levels of testosterone in men have been linked with higher rates of cheating, though it remains to be seen whether there is any such correlation in women.