White noise or pulse heard in one ear?

You have wax over your eardrum. They need syringing.

OK, Anything that we “hear” that our brain interprets as sound, comes from the part of the brain that is involved with the sense of hearing. So that's the 8th cranial nerve sending nerve input to the auditory cortex. Now to stimulate the 8th N you don't actually have to have sound coming into the ear, you just need to get some of the nerve fibers in the 8th nerve to fire. Another way would be to “hear sound” that wasn't coming through your ears would be to directly stimulate the nerves in the brain that serve the sense of hearing, the auditory cortex (Brodmann areas 41, 42, 22). So the”crackling”, electrical sounds you hear are either coming from something brushing up against your tympanic membrane (eardrum) or (possible but IMO less likely) something triggering your 8th CN to fire stimulating cells in the auditory cortex.

It could also be tinnitus which mind you is a symptom and not a disease and may have many causes (such as hearing damage, earwax build up, or stress).

Either way, it's most likely not harmful but nonetheless definitely bring it up with your doctor though so you can get an actual diagnosis and see if any treatment is necessary.

Stop listening music too much earphones