Simulating outer space silence on Earth is difficult, there are few places where you can achieve a truly sound and noise-free environment. The typical quiet room — such as your bedroom late at night — has an ambient noise level of about 30 decibels, caused by the rustling of sheets, the hum of the air conditioner or heater, and similar sources of white noise. Imagine being in an environment where you can hear the fluids moving in your own body.In the motion picture Gravity (Warner Bros. – 2013), during an EVA space walk NASA astronaut Matt Kowalski and Dr. Ryan Stone are performing repairs on the Hubble Telescope. Kowalski asks Dr. Stone, “What do you like best about this place?” Dr. Stone responds, “Silence.”
Outer space is the ultimate silent place. If you shout in outer space, even the person right next to you cannot hear what you said. Why is this? Sound propagates (spreads) as pressure waves through a medium; such as air (gas), water (liquid) or solids such as metals, wood or glass. What we call “sounds” are actually vibrations in the air.
Because space is almost a vacuum (space that is empty of matter), there is no air and thus there is no sound. So don’t bother trying to tell your astro-buddy that his space fly is down. Unless you’re communicating through a space suit communication device he isn’t going to hear you. In the movie, Dr. Stone talks about how peaceful it is in space and she feels at peace with herself when she realizes that she might die in space after a debris field rendered their space shuttle useless for flight.
Why does Dr. Ryan feel so peaceful in space due to the lack of noise? It seems obvious to us, but I’m not sure most people can truly appreciate what it would be like to go from a world full of noise to a place void of sound.
The decibel (abbreviated dB) is the unit used to measure the intensity of a sound. There is no such thing as zero when it comes to sound. While zero decibels is technically demarcated as the threshold for the human ability to hear sound, some people can decipher sounds in the negative decibel range. Normal speaking voices are around 65 dB. A rock concert can be about 120 dB.
What if you want to measure how loud a consumer product is, for example a cell phone’s ring or the hum of an Xbox game system or computer, or a dishwasher. You are better off doing so in an environment with little to no ambient noise. Much of this type of testing is done in rooms called an anechoic chambers.