The phrase "to hear the heartbeat" means to listen and pay attention to someone's emotions or feelings, often to understand them better or to show empathy. Full definition
And possibly, you could now even hear the heartbeat of your baby through the ultrasound! (easybabylife.com)
I remember hearing your heartbeat for the first time and crying without even noticing that the tears were streaming down my cheeks. (steffysprosandcons.com)
But my chest wasn't tight, and I couldn't hear my heartbeat anymore. (romper.com)