A sonic boom reaching the ground from a supersonic aircraft typically registers between about 100 and 110 decibels, roughly as loud as a thunderclap or a nearby jackhammer. That number varies with the aircraft’s size, speed, altitude, and atmospheric conditions, but it lands most people’s experience in the range of a startling, window-rattling bang. Sonic booms are not limited to military jets, though. The same physics produces the crack of a whip, the snap of a supersonic bullet passing overhead, and the devastating blast wave of a meteor entering the atmosphere.
What Actually Makes the Bang
Any object moving through air pushes pressure waves ahead of it. When that object accelerates past the speed of sound, roughly 767 miles per hour at sea level, it outruns its own pressure waves. Those waves pile up into a single, steep shock front that trails behind the object in a cone shape. A listener on the ground does not hear the boom at the moment the aircraft goes supersonic; instead, the cone of compressed air sweeps across the landscape continuously for as long as the aircraft stays above Mach 1. What you hear is the moment that cone’s edge passes over you, delivering a sudden spike in air pressure followed by a rapid drop back below normal and then a quick return. This creates the characteristic double bang, sometimes heard as two distinct thuds a fraction of a second apart, corresponding to the pressure rise at the nose and the pressure recovery at the tail of the aircraft.
The pressure jump is small in absolute terms, usually between one and two pounds per square foot of overpressure for a typical fighter jet at cruising altitude. That does not sound like much, but it arrives almost instantaneously across a large area. Windows flex, dishes rattle, pets bolt, and anyone outside hears a crack loud enough to be mistaken for an explosion. Overpressure above about two pounds per square foot can crack glass; above five, structural damage to older buildings becomes a real concern.
Putting the Loudness in Perspective
Decibel readings for sonic booms depend heavily on the measuring method. Standard sound-level meters using A-weighting, the scale designed to match human hearing sensitivity, tend to undercount the low-frequency energy that dominates a boom. Perceived loudness metrics, which account for the startle factor and the full frequency content of the pressure pulse, give higher numbers. In aerospace research, sonic booms are often reported in perceived level decibels, abbreviated PLdB, which better captures how jarring the event actually feels.
For a large supersonic transport like the Concorde, ground-level booms measured around 105 PLdB. Smaller military jets at higher altitudes produce somewhat lower values, often in the low 100s. For comparison, standing next to a running chainsaw puts you at about 110 dB, a rock concert runs 100 to 120 dB, and normal conversation sits near 60 dB. The boom itself lasts less than a second, but the perceived loudness is high enough that most people describe it as alarming even when they know it is coming.
Altitude matters enormously. A jet flying supersonic at 50,000 feet delivers a much weaker boom at the ground than the same jet at 20,000 feet, because the shock wave has more atmosphere to pass through and loses energy along the way. Aircraft size also plays a role: a larger airframe displaces more air and produces a stronger initial shock. Speed above Mach 1 has a subtler effect; going from Mach 1.2 to Mach 2 does not double the boom’s intensity, though it does change the shape and duration of the pressure signature.
The Oklahoma City Experiment
In 1964, the United States government ran what may be the most ambitious (and most controversial) sonic-boom study ever attempted. For six months, military jets flew supersonic routes over Oklahoma City, producing eight sonic booms a day in a deliberate effort to gauge how a civilian population would react to routine booms from a planned supersonic transport program.1Radical History Review. The Oklahoma City Sonic Boom Experiment and the Politics of Supersonic Aviation Residents filed thousands of complaints and hundreds of damage claims for cracked plaster and broken windows. The experiment became a turning point in American aviation policy: public backlash contributed to the eventual cancellation of the U.S. supersonic transport program and to the Federal Aviation Administration’s ban on civil supersonic flight over land, a rule that remains in effect today.
The Oklahoma City data showed that even relatively modest booms, in the range of one to two pounds per square foot, generated widespread annoyance. People could tolerate one or two unexpected booms, but daily repeated exposure provoked real anger. The psychological dimension turned out to matter as much as the raw decibel count. A boom that measured the same on instruments felt worse if it woke someone from sleep, interrupted a phone call, or arrived without warning. This finding has shaped every subsequent effort to design quieter supersonic aircraft, because the goal is not just a lower number on a meter but a sound that people can actually live with.
The Crack of a Whip and Other Everyday Sonic Booms
You do not need a jet engine to break the sound barrier. The sharp crack you hear when someone snaps a whip is, in fact, a miniature sonic boom. The loop that travels down a whip accelerates toward the tip, and the thin, light end of the whip can exceed the speed of sound, generating a tiny shock wave.2PubMed. Shape of a cracking whip The effect has been confirmed by high-speed photography and mathematical modeling of the whip’s motion.3Physica D: Nonlinear Phenomena. Whip waves The crack is brief and quiet compared with a full-size aircraft boom, but the underlying physics is identical: compressed air piling up faster than the speed of sound.
Supersonic bullets produce a similar phenomenon on a more dangerous scale. A high-velocity rifle round traveling faster than the speed of sound trails its own small shock cone, and anyone standing near the bullet’s trajectory hears a sharp snap before the deeper bang of the muzzle blast reaches them. Measurements taken downrange of an SA80 rifle showed three distinct features in the sound waveform: the bullet’s shock wave, a ground reflection, and the muzzle blast itself. At 50 meters, the shock wave arrived about 94 milliseconds before the muzzle blast; at 300 meters that gap stretched to over half a second.4Applied Acoustics. Factors affecting sound exposure from firing an SA80 high-velocity rifle This time separation is what lets experienced soldiers distinguish the crack of a passing round from the report of the gun that fired it, and it is the same physics producing both sounds: a shock wave from a supersonic object and a separate pressure pulse from the source.
The acoustic energy in these ballistic shock waves is not trivial. Research on the auditory risk of bullet-generated shock waves found that even at the distances tested, the pressure pulses posed a hearing hazard to unprotected listeners. The risk increased as the listener got closer to the bullet’s path and as bullet velocity rose.5PubMed. Auditory risk of exposure to ballistic N-waves from bullets Longer, faster projectiles generated worse exposures. This is why hearing protection on a firing range protects against more than just the muzzle blast; the supersonic crack is its own distinct threat to the ear.
Natural Sonic Booms From Meteors, Volcanoes, and Lightning
Nature produces shock waves that dwarf anything human-made. Atmospheric shock waves can originate from meteors, lightning, volcanic eruptions, and large explosions.6AIP Conference Proceedings. Sources and propagation of atmospherical acoustic shock waves Lightning, for instance, superheats a narrow channel of air to tens of thousands of degrees in microseconds, causing the air to expand faster than the speed of sound. Thunder is the resulting shock wave after it has decayed over distance into a rumble.
Meteors, however, operate on an entirely different scale. A meteoroid entering Earth’s atmosphere at tens of kilometers per second is traveling far above Mach 1 and can produce shock waves powerful enough to shatter windows and knock people off their feet. The 2013 Chelyabinsk event in Russia was caused by a roughly 20-meter asteroid that released energy equivalent to about 0.5 megatons of TNT, all within the atmosphere. The Tunguska event of 1908 involved a larger object, in the range of 10 to 100 meters, and released an estimated 20 megatons of energy, flattening about 2,000 square kilometers of Siberian forest.7Annual Review of Earth and Planetary Sciences. From Tunguska to Chelyabinsk via Jupiter In both cases the damage was done almost entirely by the atmospheric shock wave, not by an impact crater. At Chelyabinsk, the boom blew out windows across the city and injured roughly 1,500 people, mostly from flying glass.
Volcanic eruptions can also produce supersonic pressure waves. The 1883 eruption of Krakatoa sent a pressure pulse around the globe multiple times, detectable on barometers thousands of miles away. More recently, the 2022 eruption of Hunga Tonga-Hunga Ha’apai generated an atmospheric shock wave measured by weather stations worldwide. These events are rare, but they illustrate how the basic sonic-boom mechanism scales: the faster and larger the disturbance, the more energy packed into the shock front.
How the Atmosphere Bends and Blocks Sonic Booms
A sonic boom does not travel in a straight line from aircraft to ground. The atmosphere refracts and bends the shock wave depending on temperature, wind, and humidity at different altitudes. Temperature inversions, where a layer of warm air sits above cooler air, can cause the boom to bend upward and never reach the ground at all. This effect is called Mach cutoff, and it is one reason why supersonic aircraft at high altitude and moderate speed sometimes produce no audible boom at the surface.
The physics gets complicated in layered atmospheres. Research on the Mach cutoff phenomenon has shown that temperature inversions can create multiple upward and downward deflections of the shock wave, producing a pattern of outgoing and fading waves with shock-wave focusing at certain points.8Physics of Fluids. Mach cutoff phenomenon of sonic boom in temperature inversion layers In practical terms, this means a single supersonic flight can produce a boom that is loud in one neighborhood and inaudible a few miles away, depending on the atmospheric profile that day. Residents near military training routes often report wildly inconsistent experiences with booms from the same type of aircraft on different days, and atmospheric refraction is a big part of why.
Humidity and wind gradients add further complexity. A strong headwind at altitude can effectively slow the aircraft’s ground-relative speed, altering the shape and footprint of the boom cone. High humidity can absorb some of the higher-frequency energy, making the boom feel more like a low thud than a sharp crack. None of these factors change whether a boom occurs, but they heavily influence how loud it is when it arrives and where on the ground it lands.
When Sonic Booms Hit Water
Most sonic-boom research focuses on what happens at the ground, but supersonic flights over oceans raise a different question: how deep does the boom penetrate? Simulations prepared for the FAA and Department of Transportation found that sonic booms affect underwater noise levels to depths of at least 15 feet in the frequency range of about 0.15 to 200 Hz, with the most significant excess above natural ocean ambient noise occurring around 10 Hz even at depths of 100 feet. Field measurements confirmed that boom energy could travel no deeper than roughly 164 feet into the water.9Journal of Student Research. Aircraft-Produced Sonic Booms and Marine Life
That might sound like a shallow penetration, but many marine species spend significant time in the upper water column. Whales, dolphins, sea turtles, and fish with swim bladders are all sensitive to low-frequency pressure changes. A sudden pulse at 10 Hz, well within the hearing range of many cetaceans, arriving from above could startle or disorient animals near the surface. The concern is not that a single boom would cause mass die-offs but that repeated supersonic overflights along regular routes could create chronic disturbance in sensitive habitats, particularly in feeding or breeding areas. This is one of the less-discussed reasons that supersonic route planning over oceans still involves environmental review, even though there is no human population underneath to complain.
Designing a Quieter Boom
The central engineering challenge of modern supersonic aircraft design is not making a plane go fast; that problem was solved decades ago. The hard part is making the boom quiet enough that overland supersonic flight becomes politically and socially acceptable. NASA’s X-59 Quiet SuperSonic Technology aircraft, currently in testing, is designed to reshape the shock wave so that instead of the classic sharp N-wave, it produces a softer, more gradual pressure change. The target is a perceived loudness around 75 PLdB at ground level, roughly the sound of a car door closing from across the street, compared with the Concorde’s 105 PLdB.
The X-59 achieves this through a long, slender fuselage with a specially shaped nose and carefully positioned engines. The idea is to prevent the individual shock waves from the nose, wings, engine inlets, and tail from merging into one big double bang. Instead, each small shock arrives at the ground separately and at lower intensity, producing a soft thump rather than a crack. Whether this will be quiet enough for communities to accept is the question NASA plans to answer by flying the X-59 over select U.S. cities and surveying residents about what they hear and how they feel about it.
If the community response data shows that people can tolerate a 75 PLdB thump on a regular basis, it could lead to the first revision of the overland supersonic flight ban since the 1970s. Several private companies are developing supersonic business jets and airliners with similar quiet-boom goals, betting that the regulatory landscape will eventually shift. The stakes are high: the difference between a 105 PLdB bang and a 75 PLdB thump is not just 30 units on a scale. In perceived loudness terms, that gap represents roughly an eightfold reduction in how loud the sound feels to a human ear, because decibels are logarithmic. Every 10 PLdB reduction cuts perceived loudness roughly in half.
Why Sonic Booms Sound Different From Other Loud Noises
A sonic boom at 105 dB and a rock concert at 105 dB are not the same experience, even though the number is identical. Duration and frequency content matter enormously. The boom lasts a fraction of a second and concentrates its energy in low frequencies, below about 100 Hz. A concert sustains high sound levels for hours and spreads energy across a much wider frequency range. The boom’s brevity is why it startles rather than deafens: you get a sudden jolt of pressure rather than a sustained assault on the hair cells of the inner ear.
That said, the startle response itself carries real consequences. Studies of communities near military bases and supersonic training corridors have documented sleep disruption, elevated stress hormone levels, and complaints ranging from anxiety to property damage. Livestock have stampeded, and horses have been injured jumping fences. The Oklahoma City experiment and similar military studies from the 1960s showed that even modest booms, if they arrive repeatedly and unpredictably, generate public opposition far out of proportion to what the raw decibel number would suggest. A chainsaw at 110 dB is something you can choose to walk away from. A sonic boom at 100 dB arrives without warning, shakes your house, and is gone before you can identify what happened. That unpredictability is what makes the experience feel more threatening than the number alone would indicate.
Sonic Booms on Other Planets
Earth is not the only place where shock waves matter. Any atmosphere dense enough to carry pressure waves can host a sonic boom, though the speed of sound changes depending on the gas composition and temperature. On Mars, where the atmosphere is almost entirely carbon dioxide and about 100 times thinner than Earth’s, the speed of sound is lower, around 540 miles per hour. The thin atmosphere means a shock wave carries far less energy per unit area, so a Martian sonic boom would be much quieter than its Earth equivalent. NASA’s Ingenuity helicopter on Mars never approached supersonic speeds, but future faster vehicles operating in the Martian atmosphere would face a very different acoustic environment.
On Venus, the dense, hot carbon-dioxide atmosphere raises the speed of sound to over 800 miles per hour. An object would need to move faster to create a boom, but once it did, the thick atmosphere would transmit the shock wave very efficiently. On Titan, Saturn’s largest moon, the cold, dense nitrogen atmosphere produces a speed of sound around 400 miles per hour, and the thick air could carry shock waves over long distances. None of this is practically relevant yet, but as planetary exploration advances, understanding shock propagation in non-Earth atmospheres will matter for vehicle design and for interpreting acoustic data from future missions equipped with microphones, as the Mars Perseverance rover already is.