Re the two-speed fan setup;

High speed is definitely noticeable from outside the vehicle. I've heard it up to 30 ft. away from the vehicle.

You should be able to hear the difference when running ac or defroster.

Low speed is barely noticeable.....my $.02

Is the smoke alarm in your house also known as the dinner bell? '99 Zetec VCT Daily Driver Mild Air Filter Mod