Fascinating video shows how humans can actually hear the difference between hot and cold water

With daily brews and water refills, have you ever stopped to think about the difference in sounds it makes? Me neither!

Well, one TikTok video put this to the test, challenging viewers to guess the temperature based solely on the audio of pouring water.

The video shows shows a black screen whilst the sounds of hot and cold water being poured into a cup play separately. The audience asked if they could tell which is which, and comment their answers below.

Viewers had to guess the temperature based solely on the sound of pouring water / Jadroppingscience / TikTok

A lot of viewers guessed correctly in the comments that the first audio was cold water and the second was hot.

The video then explains that the viscosity of water changes with temperature, resulting in a different sound.

The molecules in cold water have less energy and therefore are less 'excited'. This means they move less rapidly and so almost bunch together more than warmer water.

Whereas, warmer water has a lower viscosity (or thickness) which makes it 'runnier' when its poured. Although you can't visually see the difference, you can hear it.

According to Naked Scientists, cold water creates 'lower-frequency sounds.' Viewers agreed, noting that hot water sounds 'dense' with 'bubbles,' while cold water sounds 'light and airy.'

Some hot-drink lovers claimed they could even sense the higher pitch of hot water and shared their experiences, like: 'as a British person who drinks tea, hot water is easily identified' whilst another said: 'as an electric kettle owner, two is obviously hot.'

Cold water creates 'lower-frequency sounds' / Photographer, Basak Gurbuz Derman / Getty

Other viewers have said the sounds are different due to the 'sound of the water hitting the cup'.

This is quite correct in that scientists explain that hotter water produces higher pitched sounds when it's 'splashing down into a mug or the bottom of a shower' due to the molecules moving around 'more than in cold water.'

Another video concurred that it is easier to see the difference in heated and cold liquid if you try it with honey. Science presenter Steve Mould said:

'With water this is less visually apparent, but when you pour water, the way it splashes into a cup is affected by the viscosity.

'This is easier to see with a liquid like honey - warm honey is more runny than cold honey.'

After years of regularly filling our glasses and cups with water - and many of us embedding daily brews into our routines - our brains have subconsciously picked up on and learned these subtle changes over time. Think about that next time you pour yourself a caffeine fix!