Start with your device volume low. Very low tones may be inaudible on phone or laptop speakers; very high tones can be uncomfortable on headphones.
What does 81 Hz sound like?
81 Hz is a bass frequency. It is a low bass tone – a warm hum similar to the low strings of a cello or bass guitar. Phone speakers reproduce it weakly; headphones work much better.
A 81 Hz sound wave completes 81 cycles every second, so one cycle lasts 12.3 ms. In air at 20 °C, where sound travels at about 343 m/s, each wave is 4.23 m (13.89 ft) long; in water it stretches to 18.28 m because sound moves about 4.3 times faster there.
Musically, 81 Hz is 30 cents below E2 (82.41 Hz) in standard A440 tuning. Doubling it to 162 Hz raises the pitch by one octave; halving it to 40.5 Hz lowers it by one.
Wavelength of 81 Hz in different materials
| Medium | Speed of sound | Wavelength |
|---|---|---|
| Air (20 °C) | 343 m/s | 4.23 m |
| Fresh water | 1,481 m/s | 18.28 m |
| Seawater | 1,500 m/s | 18.52 m |
| Helium | 1,007 m/s | 12.43 m |
| Steel | 5,960 m/s | 73.58 m |
| Glass | 5,640 m/s | 69.63 m |
Harmonics and octaves
Real instruments playing 81 Hz also produce harmonics at whole-number multiples of the fundamental. Their relative strength gives each instrument its timbre.
Which animals can hear 81 Hz?
Can hear it
Humans, Dogs, Cats, Horses, Cows, Pigs, Goats, Guinea pigs, Ferrets, Elephants, Bottlenose dolphins, Tree frogs, Goldfish, Catfish, Tuna
Cannot hear it
Sheep, Rabbits, Rats, Mice, Gerbils, Hedgehogs, Raccoons, Opossums, Chinchillas, Bats, Beluga whales, Chickens, Canaries, Budgerigars (parakeets), Cockatiels, Owls, Bullfrogs, Greater wax moths
Instruments and voices that can play 81 Hz
Frequently asked questions
What does 81 Hz sound like?
It is a low bass tone – a warm hum similar to the low strings of a cello or bass guitar. Phone speakers reproduce it weakly; headphones work much better.
Can humans hear 81 Hz?
Yes. 81 Hz is inside the typical human hearing range of 20 Hz to 20 kHz.
What musical note is 81 Hz?
81 Hz is 30 cents below E2, which is 82.41 Hz in standard A440 tuning.
What is the wavelength of 81 Hz?
About 4.23 m in air at 20 °C and 18.28 m in water.
Can dogs hear 81 Hz?
Yes – dogs hear roughly 67 Hz to 45,000 Hz.