Ever notice that your friend will talk a certain way around you, but as soon as their significant other calls, their voice suddenly changes? Well they’re not the only ones that do it. In fact, it’s a common phenomenon for someone to change pitch of their voice when talking to someone they’re romantically interested in, and it’s all because they want to make that love connection, a study says.

This change in tonality is so apparent that when researchers recorded the phone calls of 24 people, all of whom had just started a romantic relationship with someone, their voices were easily distinguishable between those who were speaking to their newfound love and those who were speaking to their closest friends.

For the study, the 24 callers were asked to call either their partner or their closest friend of the same sex. They were told to engage in conversation by specifically asking, “how are you?” or “what are you doing?” Their recordings were then replayed for a group of 80 participants who judged the sound clips on the pleasantness, sexiness, and degree of romantic interest, with some clips playing for as little as two seconds. Even with the two second clips, participants were able to tell with “greater than chance” accuracy who was talking to their partner, and who was talking to their friend.

“Vocal samples directed toward romantic partners were rated as sounding more pleasant, sexier, and reflecting greater romantic interest than those directed toward same-sex friends,” the researchers wrote, according to a press release.

They found that when it came to the callers’ voices, both men and women tried to match or mimic the tonality and pitch of their partner’s voices. Specifically, women lowered their pitch, while men made theirs higher. Doing this “represents desire for affiliation and intimacy,” and helps communicate a relational connection nonverbally.

Their vocal alterations were so apparent that listeners were able to distinguish other emotions in the short amount of time too, such as nervousness. “There was a vulnerability associated with the voices of those newly in love,” Dr. Susan Hughes, lead author of the study and associate professor of psychology at Albright College, said in the statement. “Perhaps people don’t want to be rejected.”

Source: Farley S, Hughes S, LaFayette J. People Will Know We Are in Love: Evidence of Differences Between Vocal Samples Directed Toward Lovers and Friends. Journal of Nonverbal Behavior. 2013.