Alternator whine through the inverter

A whining noise that changes pitch with engine RPM, heard through your inverter's AC output (in speakers, on a monitor, etc.), is a classic alternator whine getting picked up electrically and passed through the inverter — it's noise on the DC side bleeding into the AC output. Ferrite chokes on the DC-DC charger cables sometimes help; a proper isolated DC-DC charger with better filtering is the more permanent fix. Does the whine track with engine RPM changes?