Sound

Physics -What is sound? It is simply a movement (vibration) of air particles. Just as you can feel the vibrations of someone walking on a wooden floor, your ears can "feel" or hear the vibrations produced from their footsteps. As people talk, their breath causes vibrations in the air; we call that sound a "voice", and our ears are sensitive enough to hear those vibrations.

Sounds will travel through the air at about 760 miles per hour (at sea level). It takes sound almost 5 seconds to travel a mile. TIP: If you see lightning in an approaching storm, just begin counting...for every five seconds you count, the lightning is one mile away from you!

The three characteristics which are used to quantify sound are amplitude and frequency.
Psychoacoustics - Closely related to the measurable characteristics of amplitude and frequency are the subjective judgements of loudness and pitch.

Timbre is that trait of a sound that musical instruments have that allow their sound to be distinguished one from another even though the pitch and loudness are the same.