Sound Definition: The sound is a mechanical wave, an oscillation of pressure transmitted through a solid, liquid or gas, composed of frequencies within the range of hearing. 
Hearing Definition: Hearing, auditory perception, or audition is the ability to perceive sound by detecting vibrations changes in the pressure of the surrounding medium through time through an organ such as the ear. Sound may be heard through solid, liquid or gaseous matter. It is one of the traditional five senses. 
Hearing is the first sense developed by the 12th week of pregnancy and the only sense that never "sleeps".
[1 ^ The American Heritage Dictionary of the English Language, Fourth Edition, Houghton Mifflin Company, 2000, archived from the original on June 25, 2008, retrieved May 20, 2010]
Sound Affects Us
Sound affects us in the following levels:
Research has shown that there are particular biochemical responses to music in the human body, which can lead to changes in the heart rate, hormone secretions and brain function.
Just think: Next time you hear a pneumatic drill, try to feel your heartbeet.
According to the Tokyo Institute of Psychiatry, there is a change in the mental state of people while listening to music.
Just think: A sad pop song or Bethoven’s Moonlight Sonata, will most certainly make you feel sad.
Along with these psychophysiological effects, music has an impact on memory as well: a musical piece can facilitate learning and recall. It was found through research, that the rhythm and loudness of background music interfered with the attention span of the students.
Just think: You still recall the lyrics of that jingle in the TV commercial of your childhood...
Many studies correlate a modification of behavior caused by the presence of music.
Just think: A fast rock song played loud, will make you feel like Michael Schuhmacher when you drive and this will have an impact on your speed!
- attracts attention.
- it’s perceived even when we don’t actually watch.
- requires less cognitive effort and acts unconciously.
- helps to memorability.
- vehicle a vast amount of values instantly.
- create strong emotional bonds.
- transcends cultural and language barriers.