How do you stop a whistle from making noise?

Stopping an unwanted whistling noise requires identifying and modifying the specific restriction, gap, or vibrating surface causing the high-pitched sound. If the whistling comes from your HVAC system, you can usually stop it by replacing a clogged air filter, opening fully any partially closed supply registers, and sealing leaks in accessible duct joints with mastic tape. If the whistling is caused by environmental drafts around windows or doors, applying weatherstripping or door sweeps will eliminate the air gaps. For whistling caused by architectural features interacting with outdoor wind, physical modifications or sealing exterior gaps are necessary. You can verify that your solution was successful by testing if the high-pitched tone disappears completely once the adjustments are completed.