Static speaker sound

my iPhone 11 makes random static noises. I can be using the phone browsing something with no sound then randomly my phone will make little “ccchhh, ccchhh, ccchhh, ccchhh” sounds very low not loud, but loud enough for me to go wtf?! It sometimes last up to a minute other times last only 10 seconds. It also happens when the phone is just sitting on the table locked without me touching it. I’ve been able to time it well sometimes where I open the voice recorder and it records and the sound still emits but can’t be picked up by the mic, other times if it’s happening I open Spotify or a video and play audio, the sound goes away. Bought it new 6 months ago, has always been cased, hasn’t been near water or steam or dust or sand. Has anyone else had this happen??