There's a commonality of people who claim to be Targeted Individuals (TI) and claim they are gangstalked with Directed Energy Weapons (DEW) who report hearing that. ELF and 1mm MW range frequencies.
ELF is all around us. It fucks with your melatonin. Any vitamin aisle has it. National Institute of Health: https://www.ncbi.nlm.nih.gov/pmc/articles/PMC3553569/