piano

i was playing some Beethoven on my keyboard the other day and realized that there was a lot of physics involved in the music i was making. Each time i pressed down on a key, sound waves were produced and came out of the speakers. These longitudinal mechanical waves moved through the medium, air, to my ear. i played the note A, and remembered that A has a frequency of 440 Hz. i moved down the keyboard and played another A. This note was an octive lower and therefore had a frequency of 220 Hz.

sound2

So tonight i was listening to some kelly clarkson, my favorite american idol, and the music was pretty lound. My dad came into my room and told me to turn it down. so i turned down the volume and the music got softer. I quickly realized that this simple act is an example of physics. As i turned down the volume i decreased the sound intensity. Sound intensity is the sound of power per unit of area (intensity=power/area) Turning the volume knob down on my amplifier decreased power to the speakers and therefore decreased the intensity of sound. This same action also decreased the sound level. Sound level is the loudness. While sound intensity is objective, sound level is subjective.