Research Rack: Glossary

absorb ­ to take in and not reflect

decibel ­ a unit that measures the "loudness" of sound on a scale from zero (a sound that most people can just barely hear) to about 130 or more for sounds that cause pain

energy ­ the ability to move things

frequency ­ the number of vibrations or cycles in a given period of time

Hertz ­ a unit of frequency indicating one vibration or cycle per second

longitudinal wave ­ a wave that vibrates in the same direction as its length

loudness ­ the amount of energy a sound has

medium ­ a substance through which sound travels

molecules ­ small parts of matter

natural frequency ­ the frequency at which an object vibrates best

periodic ­ occurring at regular intervals; consisting of repeated stages

pitch ­ how high or low a sound is

reflect ­ to bounce off

resonance ­ a condition in which the frequency of an external force matches the natural frequency of the object it is acting upon

sound ­ a form of energy caused by vibration

vibration ­ a periodic motion of particles; a back and forth wave movement of sound