Do you use a cable TV provider for TV, internet and/or phone? If so, make sure the coax is grounded near the point where it enters the house/building. This should be passing through a grounding block at the electrical meter box or if it enters farther from the meter box, it should be grounded to a cold water pipe or the breaker panel. If the building has PEX or some other non-conductive plumbing, this is difficult but IT IS REQUIRED by the National Electrical Code in articles 770, 805, 810, 820, 830 and 840. It's also covered by ANSI/TIA-607-B.
Cable installers frequently neglect to ground the cable feed and it can not only cause this kind of noise, it's a safety hazard- NEC REQUIRES grounding-it's not optional and if it's not grounded, the provider should repair this code violation.
Disconnect the cable at the modem or cable box and if the noise stops, call the provider and demand that they make it right.
If they refuse, you have at least two options- change providers or install a DC block on the cable, but the latter won't work if the cable company needs a direct connection to their system.