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How loud is the SLS rocket launch?

127–136dB max1.5 to 5.2 km from the pad

BYU acousticians measured maximum overall sound levels of 127 to 136 dB at 1.5 to 5.2 km from NASA's Space Launch System during the Artemis I launch, louder than pre-launch predictions. The ignition overpressure from the solid boosters peaked at nearly 146 dB at 1.8 km.

Level
127–136 dB maxunweighted maximum sound level
Daily limit
About under 1 s a dayNIOSH, at the loud end

What the numbers mean

How it was measured. Post-liftoff maximum overall (unweighted) sound pressure levels measured by BYU during the Artemis I launch, November 2022, at stations 1.5 to 5.2 km away. The ignition overpressure peak reached nearly 146 dB at 1.8 km.

Kent Gee's team at Brigham Young University placed microphones between 1.5 and 5.2 km from the pad for Artemis I. Their 2023 paper reports post-liftoff maximum overall levels of 127 to 136 dB, greater than pre-launch predictions, and an ignition overpressure from the solid rocket boosters that was particularly intense towards the exit of the pad's flame trench.

The ignition overpressure is the sharp crack at engine start, when the supersonic exhaust suddenly heats and pushes the surrounding air. Gee writes that for Artemis I it reached nearly 146 dB at a distance of 1.8 km, above the ear's pain threshold. Much of the energy is very low in pitch: the paper found the average maximum one-third-octave peak at 20 Hz, which is why unweighted and A-weighted levels differ so much for rockets.

SpaceX's Starship is louder. BYU's measurements of Starship Flights 5 and 6 put the acoustic energy of one Starship launch at about 2.2 SLS launches, or around 11 Falcon 9 launches; an earlier BYU summary of Flight 5 said four to six SLS launches. The difference reflects updated analysis across two flights.

How long is safe?

NIOSH recommends no more than under 1 s a day at 136 dBA (2 s at 127). OSHA's legal limit is 49 s. 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
127 dB max2 s2 min 51 sunder 1 s2 s
136 dB maxunder 1 s49 sunder 1 sunder 1 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.

Protecting your hearing

NASA keeps the public several kilometres away. At those distances levels can still exceed 120 dB, so earplugs or earmuffs are sensible, and essential for children.

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).

  • Screaming piha (116 dB max): this has about 35× its sound energy and sounds about 2.9× as loud.
  • White bellbird (125 dB max): this has about 4.5× its sound energy and sounds about 1.6× as loud.
  • Chrysler air raid siren (137–138 dB): it has about 4× the sound energy of this and sounds about 1.5× as loud.
  • Space Shuttle launch (142–155 dB max): it has about 50× the sound energy of this and sounds about 3.2× as loud.

Questions

How loud is SLS from the viewing areas?

BYU measured maximum levels of 127 to 136 dB at 1.5 to 5.2 km from the pad during Artemis I.

Is SLS louder than Starship?

No. BYU found one Starship launch carries about the acoustic energy of 2.2 SLS launches.

What is the loud crack at rocket ignition?

Ignition overpressure. For Artemis I it peaked at nearly 146 dB at 1.8 km.

Sources

  1. Space Launch System acoustics: Far-field noise measurements of the Artemis-I launch, JASA Express Letters (Gee et al., 2023) via PubMed. Supports: dB_low 127 / dB_high 136.post-liftoff maximum overall levels range from 127 to 136 dB, greater than pre-launch predictionsChecked 2026-11-02.
  2. Space Launch System acoustics: Far-field noise measurements of the Artemis-I launch, JASA Express Letters (Gee et al., 2023) via PubMed. Supports: Distance 1.5 to 5.2 km.at distances ranging from 1.5 to 5.2 kmChecked 2026-11-02.
  3. The roar of a rocket, Physics Today (Kent L. Gee). Supports: Ignition overpressure nearly 146 dB (at 1.8 km, same sentence).The IOP peak-pressure level during the recent Artemis 1 launch reached nearly 146 dB re 20 μ PaChecked 2026-11-02.
  4. Starship Super Heavy acoustics: Comparing launch noise from Flights 5 and 6, JASA Express Letters (Gee et al., 2025) via PubMed. Supports: Starship comparison.the acoustic energy from a Starship launch is equivalent to 2.2 Space Launch System launches or ∼11 Falcon 9 launchesChecked 2026-11-02.
  5. Sounding off: BYU researchers study the roar of SpaceX's Starship, Brigham Young University. Supports: Earlier Flight 5 comparison.One Starship launch produces the noise equivalent of 4-6 Space Launch System launches or at least 10 Falcon 9 launchesChecked 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.