Difference in sound of girl/boy heartbeat?

Leigh Ann • Baby boy #2 due 4.30.22 ❤️🥰

Anyone know if there’s any truth to the old wives tale that a boy heartbeat sounds like a train and a girl heartbeat sounds like a galloping horse? Still waiting to find out the gender, and this morning my baby’s heartbeat sounded so much like a galloping horse on my Doppler! Anyone have any experience with this theory?