The answer to 'air filter making loud noise' is that a noisy air filter is often caused by debris buildup or improper installation. The air filter may be clogged with dust, pet hair, or other particles, causing it to vibrate or rattle as air flows through it. Alternatively, the filter may not be seated properly in the filter housing, allowing air to bypass it and create a loud noise.
In most cases, the solution is to simply replace the air filter with a new one. Be sure to measure the filter dimensions and replace it with the correct size. If the noise persists after a filter replacement, it's possible there is an issue with the HVAC system's blower motor or other components that may require professional diagnosis and repair.