Rocket launches can be so loud that scientists have to make sure their sound waves don't knock over nearby buildings. Just like we need light in order to see an object, to hear something, the sound waves need to travel through a medium, which usually is air. Vibrating air molecules pass the sound along, which creates a pressure wave, which is picked up by sensors located deep in our inner ears.
The louder the sound is, the more intense the pressure of the wave it creates. Sound it measured in decibels (dB), which is a logarithmic unit used to express the ratio of a physical quantity like power or intensity. Because the relationship is logarithmic - not linear -- an increase in 10 dB equals an increase in power by a factor of 10.
A normal conversation registers at about 65 decibels. Sounds at 90-95 decibels are where humans start to experience hearing loss from sustained exposure. We start to experience pain at 125 decibels and louder. 140 decibels and up can quickly cause irreversible ear damage. One of the loudest sounds ever recorded was NASA's Saturn V rocket, which registered 204 decibels.
However, sound doesn't just have the potential to damage our hearing: powerful sound waves can cause damage to physical structures, including the very rocket producing the deafening sound. For NASA's next-generation heavy-lift rocket, the SLS, they built a 5% scale model to study the acoustics and try to predict how loud (and potentially damaging to nearby structures) the full-size rocket will be.
So, what was the loudest sound you've ever heard? Have you ever been to a space shuttle launch? As always, we welcome you to share your experiences with us in the comments section below.
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Sound is a Pressure Wave (via Physics Classroom)
"Sound is a mechanical wave that results from the back and forth vibration of the particles of the medium through which the sound wave is moving."
NASA Turns Down the Volume on Rocket Noise Through SLS Scale Model Acoustic Testing (via NASA)
"NASA engineers recently went on an auricle ride as a scale model of the Space Launch System (SLS), including solid rocket motors, was fired -- giving an 'earful' of information about how low- and high-frequency sound waves will affect the rocket on the launch pad."
NASA's Next Rocket Is So Big, the Sound of It Launching Could Damage Buildings (via VICE)
"Earlier this summer, NASA took a 'sound ride' on a small-scale SLS rocket, which gave engineers an idea of how the acoustics of NASA's massive new launch platform will work."
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