Silence is the absence of sound just like darkness is the absence of light. Silence may suggest a certain quality of peace which is associated with the cessation of noise. The lack of air or any other suitable medium prevents sound from traveling in space, and that is why nobody will ever hear your screams out there. Atoms and molecules will still vibrate, but since space is almost a complete vacuum devoid of matter, this emptiness results in an extremely low pressure caused by gravity amplifying the nothingness of space and allowing objects to attract to each other. In the void of space, the pressure is so low that all molecules want to spread out as much as possible and this expansion, leads to the development of the stars and planets. Every particle of matter, no matter how small, exerts a gravitational attraction on all other particles of matter. There is no such thing as a complete vacuum and outer space has gas, dust, radiation, gravity, and a whole host of other things, but for the most part it is silent because sound is not allowed to propagate.
Sound is only apparent when an object moves and this might come from a vibrating guitar string or an exploding firecracker, as it pushes on the air molecules closest to it. Those displaced molecules will bump into their neighbors, and then those displaced molecules will bump into their neighbors as they travel through the air as a wave. When the wave reaches your ear, you perceive it as sound. Aging and exposure to loud noise may cause wear and tear on the hairs or nerve cells in the cochlea that send sound signals to the brain. When these hairs or nerve cells are damaged or missing, electrical signals aren’t transmitted as efficiently, and hearing loss occurs. Higher pitched tones may become muffled to you.
Silence can make you hear things that are not there, as your brain will create noise to fill the silence, especially if it is a prolonged silence. Sound is a constant in our lives every day, and most times we don’t even think about it. Zero decibels dBA is considered the point at which humans can start to detect sound. Since sound is usually measured with microphones and they respond proportionally to the sound pressure, it is possible to have negative sound levels, which would mean a sound with pressure x times smaller than the reference pressure, but these sounds would not be audible to a human. Any sound that is too quiet for humans to hear is given a negative decibel rating. For some sounds, a dog’s hearing is really hundreds of times better than ours, whereas for other sounds, dogs and humans have sound sensitivities that are very much the same. Dogs can discern sounds down to -15 decibels and dogs do much better than humans with higher-pitched sounds.
Some dogs are able to predict earthquakes using their highly sensitive ears, and others have the ability to predict somebody’s arrival at your door detecting the sound before you can hear it. Human ears have a maximum sensitivity of 2,000 Hz, which coincidentally, that frequency is right in the middle of the range of human speech. On the other hand, dogs have a maximum sensitivity of 8,000 Hz, much comes from being ancestors of wolves and this is better suited to hearing their prey. For humans, any sound over 85 decibels is considered to have the potential to cause permanent hearing loss. The closer you are to the sound and the longer you listen to it, the more likely it is to cause damage.
Written for Mindlovemisery’s Menagerie Tale Weaver – The Sound of Silence – hosted by Stephanie Colpron of Word Adventures.