Hush to Boom home

How loud is a sonic boom?

75–110dB maxon the ground beneath the flight path

Sonic booms are measured as overpressure: NASA lists Concorde at 1.94 pounds per square foot at Mach 2 and 52,000 feet. On the Perceived Level scale used for booms, Concorde's is reported at about 110 PLdB, while NASA's X-59 is designed to produce a 75 PLdB "thump". PLdB is a separate loudness metric, not dBA.

Level
75–110 dB maxunweighted maximum sound level
Daily limit
About 1 min 29 s a dayNIOSH, at the loud end

What the numbers mean

How it was measured. Figures are Stevens Mark VII Perceived Level (PLdB), a loudness metric designed for sonic booms; they are not A-weighted or flat sound pressure levels and should not be compared directly with dBA figures. 75 PLdB is the X-59's design target; about 110 PLdB is reported for Concorde at Mach 2. NASA itself describes boom strength as overpressure in pounds per square foot.

A sonic boom is a sudden pressure jump from the shock waves of an aircraft flying faster than sound. NASA measures it in pounds per square foot (psf) of overpressure above normal atmospheric pressure, which is 2,116 psf. Its fact sheet lists typical overpressures of 0.9 psf for the SR-71 at Mach 3 and 80,000 feet, 1.94 psf for Concorde at Mach 2 and 52,000 feet, and 1.25 psf for the Space Shuttle on its landing approach at Mach 1.5 and 60,000 feet. Overpressures of 1 to 2 psf are produced by supersonic aircraft at normal operating altitudes.

Because a boom is so brief, ordinary decibel readings describe it poorly. Researchers use Perceived Level (PL, quoted as PLdB), which accounts for frequency content and the rise time of the pressure jump. NASA's X-59 is designed to produce a Perceived Level of 75 dB in a standard atmosphere, which simulations suggest it would not exceed under the flight path. Trade press reports Concorde's boom at about 110 PLdB at Mach 2.

Rocket boosters returning to the launch site make booms too. BYU measured the flyback boom of SpaceX's Super Heavy booster during Starship Flight 5 at more than 10 psf at 10 km, several times Concorde's cruise figure.

How long is safe?

NIOSH recommends no more than 1 min 29 s a day at 110 dBA (no limit at the quiet end, 75). OSHA's legal limit is 30 min. This is a maximum, so a time limit based on it is a worst case. This level is not A-weighted, so the times are approximate: low-pitched sound measures lower in dBA.

LevelNIOSH limit (85 dBA, 3 dB rule)OSHA limit (90 dBA, 5 dB rule)UK/EU 80 dB(A) action value reached afterUK/EU 85 dB(A) action value reached after
75 dB maxNo limitNo limitNot reached in 24 hNot reached in 24 h
110 dB max1 min 29 s30 min29 s1 min 31 s

Times are for a whole day’s exposure, with the rest of the day quiet. The workplace limits were written for adults at work, not for children. Work out a mixed day with the noise dose calculator.

Pets

The sudden bang of a boom startles dogs and livestock. If a booster landing or supersonic test is announced near you, keep pets indoors.

Protecting your hearing

Booms are brief and seldom harmful to hearing at normal overpressures, but they startle people and animals. Near rocket landing zones, follow official advisories and keep pets indoors.

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.

Compared with sounds nearby

Using midpoints of each range. Energy multiplies by 10 every 10 dB; perceived loudness roughly doubles (why).

  • Smoke alarm (85 dB): this has about 5.6× its sound energy and sounds about 1.7× as loud.
  • Birdsong (74–103 dB max): this has about 2.5× its sound energy and sounds about 1.3× as loud.
  • Coquí frog (95 dB max): it has about 1.8× the sound energy of this and sounds about 1.2× as loud.
  • Cicada (85–108.9 dB max): it has about 2.8× the sound energy of this and sounds about 1.4× as loud.

Questions

How loud was Concorde's sonic boom?

NASA lists an overpressure of 1.94 pounds per square foot at Mach 2 and 52,000 feet. On the Perceived Level scale it is reported at about 110 PLdB.

How quiet is the X-59's boom?

The X-59 is designed for a Perceived Level of 75 PLdB in a standard atmosphere, a quiet "thump" rather than a boom.

Is PLdB the same as dBA?

No. PLdB is a loudness metric built for impulsive booms, taking account of rise time and frequency content. It cannot be compared directly with dBA readings.

Sources

  1. NASA Dryden Fact Sheet: Sonic Booms, NASA. Supports: Concorde overpressure 1.94 psf.Concorde SST: 1.94 pounds, speed of Mach 2, 52,000 feetChecked 2026-11-02.
  2. NASA Dryden Fact Sheet: Sonic Booms, NASA. Supports: SR-71 overpressure 0.9 psf.SR-71: 0.9 pounds, speed of Mach 3, 80,000 feetChecked 2026-11-02.
  3. NASA Dryden Fact Sheet: Sonic Booms, NASA. Supports: Shuttle overpressure 1.25 psf.Space Shuttle: 1.25 pounds, speed of Mach 1.5Checked 2026-11-02.
  4. Simulations of X-59 Low-Booms Propagated Through Measured Atmospheric Profiles in Galveston, Texas, NASA Technical Reports Server. Supports: dB_low: 75 PLdB.X-59 is designed to have a Stevens Mark VII Perceived Level (PL) of 75 dB in a standard atmosphereChecked 2026-11-02.
  5. The Next NASA X-Plane: Born To Boom, Machine Design. Supports: dB_high: about 110 PLdB (Concorde).The Concorde generated a boom of about 110 PLdb when cruising at Mach 2Checked 2026-11-02.
  6. Starship super heavy acoustics: Far-field noise measurements during launch and the first-ever booster catch, JASA Express Letters (Gee et al., 2024) via PubMed. Supports: Super Heavy flyback boom over 10 psf at 10 km.the flyback sonic boom exceeds 10 psf at 10 kmChecked 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.