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1

marketrent OP t1_j98r8mb wrote

Excerpt from the linked release^1 by AIP Publishing about noise measurements taken at five stations located 1.5 km to 5.2 km from the launch pad:^2

>When the Artemis 1 mission was launched by NASA’s Space Launch System, SLS, in November, it became the world’s most powerful rocket, exceeding the thrust of the previous record holder, Saturn 5, by 13%.

>With liftoff came a loud roar heard miles away.

>In JASA Express Letters, published on behalf of the Acoustical Society of America by AIP Publishing, researchers from Brigham Young University and Rollins College in Florida reported noise measurements during the launch at different locations around Kennedy Space Center.

>The data collected can be used to validate existing noise prediction models, which are needed to protect equipment as well as the surrounding environment and community.

>These data will be useful as more powerful lift vehicles, including the SLS series, are developed.

> 

>“We hope these early results will help prevent the spread of possible misinformation, as happened with the Saturn 5,” author Kent Gee said.

>“Numerous websites and discussion forums suggested sound levels that were far too high, with inaccurate reports of the Saturn 5’s sound waves melting concrete and causing grass fires.”

>A characteristic feature of rocket launches is a crackling sound from shock waves.

>These shocks represent instantaneous sound pressure increases that are much louder than crackling noises encountered in everyday life.

>Author Whitney Coyle said, “We found the Artemis-I noise level at 5 km had a crackling quality about 40 million times greater than a bowl of Rice Krispies.”

^1 The Roar and Crackle of Artemis 1, AIP Publishing, 14 Feb. 2023, https://publishing.aip.org/publications/latest-content/the-roar-and-crackle-of-artemis-1/

^2 Kent L. Gee, et al. Space Launch System acoustics: Far-field noise measurements of the Artemis-I launch. JASA Express Letters 3, 023601 (2023); https://doi.org/10.1121/10.0016878

6

Bokbreath t1_j98rfqr wrote

>At a 5.2 km distance, the noise was 129 decibels, nearly 20 decibels higher than predicted by a prelaunch noise model.

That's about the same level as a jackhammer ... but over 3 miles away.

191

manicdee33 t1_j98rzsh wrote

The USA is best known as the country that will do anything to avoid using the metric system.

Paper this article is based on: https://asa.scitation.org/doi/10.1121/10.0016878

> Significant results include: (a) the solid rocket boosters' ignition overpressure is particularly intense in the direction of the pad flame trench exit; (b) post-liftoff maximum overall levels range from 127 to 136 dB, greater than pre-launch predictions; and (c) the average maximum one-third-octave spectral peak occurred at 20 Hz, causing significant deviation between flat and A-weighted levels.

I'm just lost on how they quantify the "crackling quality" :D

64

Aiku t1_j9964ap wrote

Welcome to r/science, where decibels are re-organized on the Rice Krispie scale. I'm curious: how many football fields did it travel?

171

vnnie3 t1_j996y6j wrote

As a research student myself, it baffles me to see such "units of measurement" in a paper

98

billsil t1_j99epup wrote

Replying to manicdee33 (#1,878,910)

Depends how much it pops.

136 dB is really loud. Also Bels are not really a unit. You take the logarithm of a pressure relative to 20 microPascals (the threshold of human hearing), so it's unitless. Deci-bels are 1/10 as large as a Bel and just make the numbers easier. Otherwise, we'd be talking about 13.6 Bels.

Beyond that I understand part of it. An octave is a power of 2, so 20 Hz to 40 Hz. The 1/3 octave part means that between 2 octaves, you have 3 bands. So for 20 Hz, the range of interest is 20/2^1/3 to 20*2^1/3 (or 15.9 to 25.2 Hz).

The USA is best known as the country that will do anything to avoid using the metric system.

That quote is metric and English friendly.

11

zdakat t1_j9a325i wrote

The true unit of measurement, "Bowl of Rice Krispies".

10

Adavis72 t1_j9a4661 wrote

New units of measurement. Snap, Crackle, Pop.

1

JohnOliverismysexgod t1_j9a91ia wrote

I like it that the unit of measurement is the sound of a bowl of Rice Krispies.

1

Araella t1_j9abrvx wrote

But what about the snap and the pop?

1

eilradd t1_j9adxll wrote

This headline reads like an onion article

9

aecarol1 t1_j9aijaf wrote

Replying to Adavis72 (#1,882,586)

You can't ask that kind of question without understanding the physics behind standardized measurements. What is the viscosity of the milk? i.e. whole milk or 2%? What is the relative humidity? Are the bowls glass or plastic?

The Cereal Experimentation Regulation Normalization board (CERN) has spent literally billons of dollars to analyze and study the sounds cereal makes and to standardize noise comparisons. At their cereal study facility in Switzerland they collide Rice Krispies at neatly the speed of light to calculate the noise they make.

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otter111a t1_j9akvfi wrote

Americans. Literally anything besides the metric system

0

brentm5 t1_j9asqpr wrote

Yeah but how many giraffes would it equal?

2

2thicc4this t1_j9ayxof wrote

I’m glad to see scientists using fun points of reference like this. Look at how much more engagement it has garnered this paper.

2

TheCosmicJester t1_j9b1j9g wrote

I now want to know the noise level if you made 40 million bowls of Rice Krispies all at once.

2

freds_got_slacks t1_j9bdpqg wrote

Replying to manicdee33 (#1,878,910)

https://asa.scitation.org/na101/home/literatum/publisher/aip/journals/content/jel/2023/jel.2023.3.issue-2/10.0016878/20230211/images/large/10.0016878.figures.online.f4.jpeg

In this figure from that paper, while the flat peak is 120 dB centred around 20 Hz, with an A-weighting this only translates to about peak 95 dBA around 200 to 1000 Hz.

Measurements for occupational safety are done with A weighting, but would there be any safety concern with an unweighted 127 dB SPL at 20 Hz? or is A weighting still sufficient ?

Edit: higher res figure

1

Mr_derpderpy t1_j9bzgdk wrote

What in the tarnation unit of hillbilly ass measurement is cereal

1

BoraxTheBarbarian t1_j9ctqkz wrote

With the launch hitting 129 dB, that would put the Rice Krispie bowl at 54 dB.

1

Fishermans_Worf t1_j9cyik8 wrote

Replying to Adavis72 (#1,882,586)

There's a simple formula for that. All weird units but it works out.

C=(3E/L)^O/D

C=Number of bowls

E=Height of the Empire State Building in smoots.

L=Information content of the Library of Congress in HD floppy discs

O=Orbital radius of Luna in yards

D=Distance to cereal in attoparsecs

1

LaMadreDelCantante t1_j9d6iqe wrote

Replying to Bokbreath (#1,878,838)

This seems odd to me. I know it was supposed to be loud, but I live about 14 miles from the launch pad and it didn't seem, by the very scientific measurement of my ears, to be any louder than any other launch, maybe even quieter.

2

sojayn t1_j9dghdl wrote

Did Little Alex Horne write this study?

1

Bigram03 t1_j9djget wrote

That is an eipc amount of energy being released...

1

BigKahuna545 t1_j9et77n wrote

Perhaps as a nod towards the metric system, scientists could use the Guinness fart.

1