Amplitude and Loudness> A sound can be as soft as a whisper, or as loud as an explosion. We call the property of how loud a sound seems to us its loudness - no surprise there - and just as with pitch and <#5680,7><!frequency>, there is a wave property, called <#5655,5100><!amplitude>, that matches it.
Toss a small pebble in the pond, and the <#5675,6><!waves> you get are small ones, just tiny ripples. Lob a big rock in, and the waves are much larger, with much higher peaks (crests), and much lower valleys (troughs). We call the height of the waves their amplitude. Surfers are always looking for ocean waves of great amplitude!
Whack a drum hard and you get big vibrations back and forth. The drum makes sound waves of large amplitude, and the sound you hear is a very loud one. Just give the drum a light tap, and the drumhead barely vibrates back and forth, only gently squeezing the air as it does so. The result is a sound wave of low amplitude, and a quiet sound of low loudness you have to strain to hear. The amplitude of a sound wave is the strength of its vibration, and the higher the amplitude, the stronger the vibration, the more energy the wave has, and the louder it will seem.
You can measure amplitude of a sound wave by measuring how hard its waves push against something. Sound scientists measure amplitude in <#5656,5104><!decibels>, abbreviated dB. A whisper measures about 20 dB. Loud, amplified music at a concert can be well over 100 dB. If the amplitude of a sound wave is too high, the intensity of the sound wave can be enough to cause damage to your ears, so it’s always a good idea to use ear protectors when you’re around loud sounds.
