Facts and Figures on Different Hearing Ranges

The human ear is an amazing organ and the sense of hearing is a fascinating one. The human ear is extremely sensitive to sounds and can detect sounds within the frequency range from 16 Hertz (Hz) to 16 384 Hz. Children are better than older people at hearing sounds at the higher frequency end of this range and damage to the ears, such as caused by exposure to loud noise, tends to reduce the range too.

How is Hearing Range Tested?

Basically, in humans the test is quite easy as the subject can communicate whether they hear a sound or not. People having a hearing range test wear noise-cancelling headphones and listen to a series of sounds at different levels, indicating whether they hear something or not. By using low frequency and high frequency sounds, it is possible to find the hearing range of individuals and to obtain data to work out the average range mentioned earlier.

The Range of Hearing in Other Mammals

Many other animals have a wide range of hearing – they can hear over a wide frequency band and most mammals have very similar hearing ranges to humans but many animals can hear sounds of much higher frequencies:

• A dog can hear sounds from 67 Hz to 45 000 Hz – which is why it can hear a dog whistle but we cannot – and maybe why the sheep are not bothered by it either as their range is only up to 30 000 Hz.
• A hedgehog can hear sounds from 250 Hz to 45 000 Hz.
• A rabbit’s range is from 360 Hz to 42 000 Hz.
• A cat can hear from 45 Hz to 64 000 Hz – putting it in the same range as a possum, which can hear sounds from 500 Hz to 64 000 Hz.
• A cow can hear sounds from 23 Hz to 35 000 Hz.
• A ferret’s range is from 16 Hz to 44 000 Hz.
• One of the mammals with the ability to hear very high frequency sounds is the mouse – it can hear sounds from 1000 Hz to 91 000 Hz. So it can still out-do the cat! A baby mouse can cry at 40 000 Hz – well out of the range of human hearing.
• Not surprisingly, a bat can hear sounds up to 110 000 Hz and it makes use of this in the specialised technique of echolocation.
• One of the few animals to have a hearing range smaller than a human is the elephant, which hears sounds between 16 Hz and 12 000 Hz..

The Range of Hearing of Aquatic Animals

Mammals that live underwater most of the time have evolved specialised hearing systems and their hearing ranges are quite different to humans and most land mammals. The fur seal and the sea lion both have a range from around 450 Hz to 50 000 Hz but the Beluga whale can hear sounds up to 123 000 Hz, much beyond the hearing range of a bat.

Harp seals can hear up to 85 000 Hz, the harbour porpoise up to 105 000 Hz and the bottle nose dolphin can also hear up to 105 000 Hz. Winner of them all in the high frequency hearing stakes is, however, the porpoise. This marine mammal has a vast hearing range from 75 Hz to 150 000 Hz.

Mammals that live in the sea have developed such wide hearing ranges to be able to use echolocation techniques to find their prey. The porpoise and the bottle nose dolphin emit very high frequency sounds and have two different types of cochlea – one specialised for very high frequency sounds – to be able to hear each other.