Whether you pluck a string on a guitar, hit a key on the piano, blow across the top of a soda bottle, beat a drum, drop a book, or sing, energy is needed to make the sound. What makes the sound louder or softer to the ear is the amount of energy the sound has. Sound gives off energy known as sound energy. A loud noise gives off more sound energy than a soft noise. Loudness also has a unit of measurement. The loudness (or volume) of a sound is measured in units called decibels. Scientists use the symbol “dB” for decibels. The softest sound that humans can hear is just less than one decibel (1-dB). Sound becomes painful or damaging to your ears at about 120 decibels (120-dB). Have you ever heard a ringing in your ears after hearing something very loud? The sounds you were listening to were too loud; sounds that loud can damage your hearing.
Measuring sound
What unit is loudness measured in?
Decibels (dB)
