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Infrasound · Frequency

7.83 Hz tone

Play a 7.83 Hz tone online, see what note it is, how long its wave is and which animals can hear it. It is infrasound – below the roughly 20 Hz lower limit of human pitch perception.

7.83Hz

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.

128 msPeriod (one cycle)
43.81 mWavelength in air (20 °C)
B-2+25¢Nearest note (A4 = 440 Hz)
NoAudible to humans

What does 7.83 Hz sound like?

7.83 Hz is a infrasound frequency. It is infrasound – below the roughly 20 Hz lower limit of human pitch perception. At high levels it is felt as pressure, fluttering or vibration rather than heard as a tone, and phone or laptop speakers cannot reproduce it at all.

A 7.83 Hz sound wave completes 7.83 cycles every second, so one cycle lasts 128 ms. In air at 20 °C, where sound travels at about 343 m/s, each wave is 43.81 m (143.72 ft) long; in water it stretches to 189.14 m because sound moves about 4.3 times faster there.

Natural infrasound comes from earthquakes, volcanoes, ocean waves, wind and thunder; whales and elephants use it to communicate across long distances.

The fundamental Schumann resonance – electromagnetic (not acoustic) resonances of the cavity between Earth's surface and the ionosphere, excited by lightning. As a sound it would be infrasonic and inaudible.

Wavelength of 7.83 Hz in different materials

MediumSpeed of soundWavelength
Air (20 °C)343 m/s43.81 m
Fresh water1,481 m/s189.14 m
Seawater1,500 m/s191.57 m
Helium1,007 m/s128.61 m
Steel5,960 m/s761.17 m
Glass5,640 m/s720.31 m

Harmonics and octaves

Real instruments playing 7.83 Hz also produce harmonics at whole-number multiples of the fundamental. Their relative strength gives each instrument its timbre.

HarmonicFrequencyNearest note
1× (fundamental)7.83 Hz–
2×15.66 Hz–
3×23.49 HzF♯0
4×31.32 HzB0
5×39.15 HzD♯1
6×46.98 HzF♯1
7×54.81 HzA1
8×62.64 HzB1

Which animals can hear 7.83 Hz?

Frequently asked questions

What does 7.83 Hz sound like?

It is infrasound – below the roughly 20 Hz lower limit of human pitch perception. At high levels it is felt as pressure, fluttering or vibration rather than heard as a tone, and phone or laptop speakers cannot reproduce it at all.

Can humans hear 7.83 Hz?

No. 7.83 Hz is below the ~20 Hz limit of human pitch perception; very loud infrasound can be felt as vibration.

What musical note is 7.83 Hz?

7.83 Hz is outside the range normally used for musical notes.

What is the wavelength of 7.83 Hz?

About 43.81 m in air at 20 °C and 189.14 m in water.

Can dogs hear 7.83 Hz?

No – dogs hear roughly 67 Hz to 45,000 Hz.