The ability to hear sound, one of the key senses in many peoples' lives, is truly a magnificent treasure. I could type a list of sounds and odds are you could immediately imagine them.
The sound of a woman in high heels walking down a marble corridor.
The sound when someone opens the tab on an aluminum can.
The sound of a log in a fire popping as it burns.
The sound of an old typewriter being used all the way to the end of the page, followed by a ding! then the slide back.
This list could go on and on. My point is, certain sounds can conjure so much in people, emotionally and sometimes even physically.
Sound is measured in decibels (dBA), with the softest sound a human can hear being 0 dBA. Talking to someone would probably result in a 65 dBA conversation, unless discussing some brilliantly contradictory topic that rose to 75 dBA as the argument continued. Humans experience physical ear damage if exposed to sound over 85 dBA for long periods of time, like attending a rock or metal concert for over an hour without giving your ears a break. Heck, a loud enough sound can even kill you on the spot, ask the guys who were there for the Krakatoa Eruption! (Or, well, maybe not...)
The sound of ice cubes clinking in a glass of water on a summer afternoon.
Now all that nonsense only has to do with how loud a noise is. The really fun parts are about the frequency of those sounds. Frequency deals with how many sound vibrations there are in a single second, and the human brain can understand a vast range of these frequencies, measured in Hertz. Still, while we can hear a broad range of frequencies, we can't hear them all. Dogs can hear significantly higher frequencies than us (which is why dog-whistles work) and some animals sense frequency changes in the air and can judge impending weather conditions from that. On the other end, there are also sounds much lower than what the human ear can comprehend; elephants communicate in lower tones than any human can hear without technological assistance.
The sound of the buzzing of a fluorescent light just turned on.
So with all this information, the question is brought forward, how does sound affect the human mind?
There's odd connections found in ghost sightings and, you guessed it, sound. Sounds lower than 20 kiloHertz can't be heard by humans, but can still be registered by the human body without the owner knowing it. These extremely low noises are called infrasound, and British lecturer Vic Tandy produced a whole series of experiments following his own experience with believing to have seen an apparition. He stumbled upon the idea of there being low enough vibrations that were registered without being heard, and that the human brain reacted to it by conjuring up a spirit. This was the first time a connection had ever been made from ghost-sightings to sound frequencies. He studied alongside Dr. Tony Lawrence and you can read their findings in Journal of the Society for Physical Research, or watch a documentary featuring their work called "Ghosts on the London Underground."
The sound of waves crashing against a shore.
Sound can even be used to help support scientific theories: specifically, the Big Bang Theory. Back in 1964, scientists Robert Wilson and Arno Penzias accidentally made the famous discovery of leftover sound from the original Big Bang. If you've heard static from a TV before, you've essentially heard what these two men found after building an antenna for Bell Labs, New Jersey, which didn't do exactly what they were expecting. They accidentally found proof of the very first photons released from the Big Bang that still exist in the universe today as radio waves. Now, you can't tell me that's not about as cool as it gets.
The sound of a drop falling into a shallow pool of water in an otherwise silent room.
Then there's always the absence of sound. Yes, in our extremely busy, noisy world, there exists sound-proofing technology. And with technology begets questions of the capabilities of humans. The record once held by the Anechoic Chamber in Orfield Labs, South Minneapolis has officially been broken for "World's Quietest Room" by the Microsoft Labs headquarters in Redmound, Washington, as officially stated by the Guinness World Records in 2015. Inside the room, the sound is at -20.1 dBA, an insanely quiet area. It was developed for device and audio testing, but one has to wonder how long someone could stay in that room, silent and alone.
In Orfield Labs, the longest anyone could remain in the room was only 45 minutes before they started to feel to panic and too freaked out to continue. They would speak of how they could hear their own stomach working and gurgling and could hear blood pumping through their bodies. So for a room now -6.9 dBA quieter, how long could one of those individuals last?
The sound outside on a windy night when you're going to sleep.
Sound moves all around us. You can feel it in the bass of a rap song that you blast while speeding down the highway the same way you can feel the high notes of a violin tantalizing your ears in an orchestral performance. Sound is an experience we're lucky to be able to both hear and feel, and while we may not have the most developed abilities to realize how much noise there truly is in the world, we're damn lucky to be able to hear what we hear.
The sound of an old, heavy book shutting for the last time.