My best guess is your AC belt is in bad shape and tightens when you engage the AC/Defrost.
it sounds lkike a little screaching noiuse
I believe the sound you are referring to comes from Cicadas.
If the fluid is ready to be changed, it will make a screaching noise when turned to extreme left or extreme right.
If you are driving and you hear a high pitch squeeling/screaching sound but when you apply the brakes the sound stops your brakes need replacing, this is called your brake squeeler.
The fake sound you hear when you have tinnitus. Also, any device that is permanently on will produce a constant sound.
The atmospheric pressure has no effect on the speed of sound when the temperature is constant. The air pressure has no influence on the sound.
Sounds like the CV (constant velocity) joints are worn and need relacing
A hog sometimes makes a snorting sound, and sometimes makes a squealing sound.
No.
yes
When sound enters another medium such as a wall, the frequency or pitch of the sound remains constant. The velocity or speed of sound may change depending on the properties of the medium, but the frequency remains the same.
If you change sound's frequency and hold the velocity constant, the sound's wavelength also changes. If you change sound's frequency and keep the wavelength constant, then velocity also changes.