HowLoudThe Loudest Sound Ever Recorded
The loudest sound in recorded history was the eruption of Krakatoa in Indonesia on 27 August 1883. A pressure gauge 160 km away registered a level estimated at about 172 dB, and the blast was heard about 4,800 km away, on an island in the Indian Ocean. Barometers around the world recorded its pressure wave passing several times as it circled the Earth.
Record-breaking sounds
| Event | Level | Notes |
|---|---|---|
| Krakatoa eruption, 1883 | ≈172 dB at 160 km | Heard 4,800 km away; pressure wave circled the globe |
| Hunga Tonga eruption, 2022 | not measured in dB at source | Heard in Alaska, about 10,000 km away; pressure wave went round the Earth several times |
| Heavy-lift rocket launch | ≈200 dB near the pad (est.) | Launch pads flood with water to protect the rocket from its own noise |
| Stun grenade | ≈170–180 dB at 1.5 m | Designed to disorient with sound and light |
| Jet engine | ≈140–150 dB at 30 m | Ground crews wear double hearing protection |
| Loudest crowd at a stadium | ≈140 dB | Peak readings near the stands |
| Thunder directly overhead | ≈120 dB | The pain threshold |
Krakatoa: the sound heard round the world
The final explosions of Krakatoa tore the volcanic island apart. People on Rodrigues, an island near Mauritius almost 4,800 km away, reported what sounded like distant cannon fire, the longest distance any sound is known to have been heard. Sailors 64 km away suffered ruptured eardrums. A gas-works pressure gauge in Batavia (now Jakarta), 160 km from the volcano, jumped by more than 2.5 inches of mercury, which corresponds to roughly 172 dB, louder at that distance than a jet engine heard from a few metres.
Why air tops out at 194 dB
A sound wave is an alternating rise and fall in air pressure around normal atmospheric pressure. At about 194 dB the low-pressure half of the wave reaches zero, a vacuum, and cannot go any lower. Anything more powerful stops being a sound wave and becomes a shock wave, a moving front of compressed air. Close to Krakatoa, or near a rocket engine, the "sound" is really a shock wave, which is why figures above 194 dB are estimates of blast pressure rather than conventional sound levels. Underwater the limit is much higher, which is how sperm whales reach about 230 dB.
How loud is that compared with everyday life?
Each 10 dB is ten times the sound energy. Krakatoa's 172 dB, 160 km away, carried about ten billion times the energy of a 70 dB vacuum cleaner. Anything above about 150 dB can rupture eardrums; at 185–200 dB the pressure wave can injure the lungs, see can sound kill you?
Frequently asked questions
What is the loudest sound ever recorded?
The 1883 Krakatoa eruption, estimated at about 172 dB at a distance of 160 km and heard 4,800 km away.
What is the loudest sound possible?
In air at sea level, about 194 dB for an undistorted sound wave. Beyond that the disturbance becomes a shock wave.
What is the loudest man-made sound?
Nuclear test explosions and rocket launches produce the highest pressures; near a large rocket at launch, estimates reach around 200 dB, which is already a shock wave rather than ordinary sound.
What is the loudest everyday sound most people hear?
Fireworks and gunshots at close range, often 140–160 dB peak, followed by sirens and concerts at 110–120 dB.