While they may look identical, hot and cold water make different sounds when poured.
Temperature affects water’s thickness. At lower temperatures, water molecules create temporary bonds that thicken the liquid, producing a lower-frequency sound when poured.
Conversely, heated water molecules are more energetic, making it harder for molecules to join together. Fewer bonds result in thinner water, which produces a noticeably higher-pitched sound when transferred into a cup.
Researchers say bubbling also plays a role in water acoustics — hot liquids have more bubbles than cool liquids, which contribute to the higher pitch that we hear while pouring out a cup of coffee or tea.
Can you hear the difference?
Source: https://interestingfacts.com