Home fetal Dopplers?


So I’m 9 weeks 5 days pregnant with baby #2. I have a home fetal Doppler that I used with my last baby, and I’ve been using it with this baby too. I’ve been using it a lot more with this pregnancy though because I’m more anxious. Then I made the mistake of getting on google to make sure these dopplers are safe, and I can’t get a straight answer! I’ve read that the sound waves can cause brain damage or hearing problems. I used it with my son, and he’s perfectly fine. But I’m more paranoid this time around. Any experiences with home fetal Dopplers?