You may have noticed how quiet it seems after a snowfall. Freshly fallen snow works in a manner similar to sound tiles -- it absorbs sound waves. As the snow becomes packed down, or more dense, its ability to absorb sound decreases. Even though snow absorbs sound, you may have noticed that sometimes when you walk on snow it squeaks. If you are a careful observer, you will have noticed that whether snow squeaks when you walk on it depends on how cold it is outside.
The freezing and boiling point of water is a function of pressure. One example of this is that it takes longer to boil an egg in the Rocky Mountains than on Long Island. Water boils at a lower temperature at high altitudes, so the egg has to cook longer. Similarly, if you increase the pressure you lower the temperature at which water will freeze. When you walk on snow, your boots apply a pressure. If the temperature of the snow is warmer than approximately 14F (-10C), then the pressure exerted by your boot partially melts the snow allowing it to 'flow' under your boot and no sound is made. When the snow is colder than -10C, the pressure from your boot does not melt the snow, and instead the ice crystals beneath your boot are crushed making a squeaking, or creaking, sound. The fact that the freezing point of water is a function of pressure, also explains why we can ice skate. The pressure exerted by the blade of the ice skate is enough to melt a very thin layer of the ice, allowing the blade to slide over the thin film of water.