The first concept to wrap your rubbery little mind around is the idea of sound. Sound isn't an object. Your boom box isn't firing little particles of magic sound dust to tickle your ears with M.C. Hammer
. Instead, sound is the transfer of energy.
A source (such as the speaker on you boom box) is receiving electrical energy and converting it into mechanical energy. If you'll kindly place your fingers against your throat and scream the phrase, "someone's already made a movie about a giant singing plant
," you'll feel that mechanical energy in the form of vibrations. You'll also have noticed those vibrations when you stand really close to a drum set or those cheap speakers your ex-girlfriend blasts Smash Mouth on.
That mechanical vibration acts like a piston pushing particles forward when it moves outward and pulling particles backwards when it pulls in. Like I said, sound isn't an object; it is a transfer of energy. Those particles are not hurling towards your ears. The first particle touches the next particle and moves it a bit. That particle moves the next particle a little bit, and so on until that movement, that energy, reaches your ear. How fast those particles transfer energy (the speed of sound) is determined by what type of particle it is. In air, sound moves at 343 meters per second. In your secret underwater sea lab it moves at 1533 meters per second (I won't tell anyone).
I know you implicitly understand this, because you're super smart, but small sources move a small number of particles and big sources move a big number of particles. If the mechanical vibration is small (if the piston only moves a short distance), it doesn't transfer much energy to the particles so the sound is small. If your speaker is really athump'n (the piston moves a large distance) it is transferring large amounts of energy and it produces large sound.
One last note on the concept of sound, we say sound is a wave. But it isn't one of those up and down waves like a jump rope or those sine graphs your algebra teacher makes you draw. It is a back and forth sort of wave featuring a series of particles pressed really close together and particles spread far apart. If you stretch a good slinky
out on the ground and give it a push (a push not a wiggle! a push I said!) you'll see another example of this type of wave.