What is the loudest possible sound?
In air at sea level, the loudest sound that can travel as an ordinary, undistorted wave is about 194 dB (peak, re 20 µPa). At that level the pressure swing equals atmospheric pressure, so the low-pressure half of the wave reaches a vacuum. Anything louder is a shock wave or blast, not a normal sound wave.
- Level
- 194 dB peakunweighted peak sound pressure level
- Daily limit
- No safe unprotected exposureimpulse noise
What the numbers mean
How it was measured. Theoretical limit in air at sea-level atmospheric pressure (101.325 kPa), expressed as peak sound pressure level re 20 µPa. The exact value shifts with barometric pressure.
Sound is a pressure wave that swings above and below the surrounding air pressure. The high-pressure half can in principle go as high as you like, but the low-pressure half cannot drop below zero: a vacuum. Guinness World Records explains that the troughs of a wave can go no lower than 0 atmospheres and, if the wave is symmetrical, the peaks reach 2 atmospheres, and that a sound wave with that amplitude range corresponds to 194 dB.
Writing for Hearing Health Matters, Wayne Staab sets out the same limit: the loudest sustained sound is a pressure wave oscillating between vacuum and +2 atmospheres, which corresponds to 194 dB SPL peak re 20 µPa and a pressure deviation of 101.325 kPa, ambient pressure at sea level. You can check the arithmetic yourself: 20 × log10(101,325 Pa ÷ 0.00002 Pa) comes to about 194 dB.
Louder events do happen, but they are no longer sound in the usual sense. Above the limit the extra energy distorts the whole wave and it becomes a blast wave with a near-vacuum behind it, which is what happens close to large explosions and volcanic eruptions such as Krakatoa. The limit is a feature of air at sea level. Underwater levels are quoted against a different reference pressure (1 µPa) and the ambient pressure is far higher, so underwater figures above 194 dB, such as sperm whale clicks, do not break this rule.
How dangerous is a 194 dB peak?
A peak of 194 dB is at or above 140 dB, the impulse limit used by NIOSH and OSHA and the EU and UK exposure limit value. A single exposure at close range can damage hearing.
| Rule | Peak limit | This sound |
|---|---|---|
| UK and EU lower exposure action value | 135 dB(C) | Above |
| UK and EU upper exposure action value | 137 dB(C) | Above |
| UK and EU exposure limit value; NIOSH and OSHA impulse ceiling | 140 dB | Above |
Protecting your hearing
Real sounds anywhere near this level are explosions. Long before 194 dB, distance is the only practical protection.
Earplug and earmuff ratings (NRR in the US, SNR in the UK and EU) are lab figures; real-world protection is usually lower. How to read the ratings.
Questions
Can a sound be louder than 194 dB?
Not as an undistorted sound wave in air at sea level. Events above 194 dB are shock waves, where the air itself is pushed along, rather than ordinary sound.
Why is the limit 194 dB?
Because at 194 dB the pressure swing equals atmospheric pressure (101.325 kPa), so the low-pressure half of the wave reaches a vacuum and cannot go lower.
Why do underwater sounds go above 194 dB?
Underwater decibels use a reference of 1 µPa instead of 20 µPa, and water is under much higher pressure, so the same rule does not cap underwater figures at 194.
Sources
- Loudest possible sustained sound in air, Guinness World Records. Supports: 194 dB limit.
A sound wave with amplitude range of 2 atmospheres corresponds to 194 dB
Checked 2026-11-02. - Loudest possible sustained sound in air, Guinness World Records. Supports: Above 194 dB is a shock wave.
Any event louder than 194 dB is considered a shock wave
Checked 2026-11-02. - An Upper Limit to Sound?, Hearing Health Matters (Wayne Staab, PhD). Supports: 194 dB SPL peak re 20 µPa.
Multiple sources identify this level at 194 dB SPL peak re 20 µPa
Checked 2026-11-02. - An Upper Limit to Sound?, Hearing Health Matters (Wayne Staab, PhD). Supports: Pressure deviation equals sea-level ambient pressure.
This level has a sound pressure deviation of 101.325 kPa
Checked 2026-11-02. - The Sound So Loud That It Circled the Earth Four Times, Nautilus (Aatish Bhatia, 2014). Supports: Independent statement of the 194 dB limit.
This limit happens to be about 194 decibels for a sound in Earth’s atmosphere
Checked 2026-11-02.
This page is general information, not medical advice. If you have ringing in your ears, muffled hearing or any change in your hearing, see an audiologist or your doctor.