Noise may refer to:
If you still do not find what you were looking for, you may make it up for yourself. Simply juxtapose random things such as obscure 80s pop bands, llamas, xylophones, the Battle of Hastings, milk, postmodernism, titanium dioxide, artichokes, Chuck Norris, etc., in a hilariously zany comedy skit. Students will love you for your high noise-to-signal ratio, and hail you as a comedic genius. Other people may hanker for the sweet release of death should they become the recipient of one of your crazy monologues. But, sonically speaking, there isn't that much difference between a cry of "AAAARGGHHH! MAKE IT STOP!!!" and an approbative guffaw. So carry on, by all means.
Also, noise can be a genre of noise - I mean music. It can kill people that listen to it or scare young children. [Zero Acid - Your Computer Looks Thirsty|http://www.last.fm/music/Zero+Acid/_/Your+Computer+Looks+Thirsty]
If you mean sound, specifically, of course, well that's different than noise. I mean, noise is a lot closer to smell - look how similar the word is to nose. Nah, screw it, there the same. Both measured by the decibel system. The dB, or decibel, system is simply a method used to describe the magnitude of noise in a room. The base unit is the bell, defined as the mean sonic amplitude made by the ringing of a single bell. For example, "Jingle Bells" has two bells in it, so the average playback of Jingle Bells can be said to have a mean sonic amplitude of "Two bells" (despite "Jinglin' all the way...").
Expanding on this concept a system was devised, historically known as the Graham system, after its inventor, a graham cracker. Today, we know it as the decibel system (deci from the pig Latin meaning "to kill", as in decimate, and bel from the Belgian word "bell", which, as I've already explained, is the mean sonic amplitude of a single bell ringing). As the name implies, the decibel system provides a measurement of the number of bells killed during a time interval. Thus, a system with more decibels (literally, "killed bells") will sound quieter.
The more bells killed, the quieter the sonic amplitude: If Tom Bell and Alice Bell are singing Jingle Bells and you kill one of them, the sonic amplitude will go from two bells to a single bell. Hence, a linear one decibel shift. It's quite simple. (A refrigerator has no bells, and thus cannot contribute to the ambient sonicity of a room.)