The greater the amplitude of sound, the “louder” it sounds. A whisper would be a low amplitude sound and a shout would be a high amplitude sound.

Changes in sound amplitude are measured in units called “decibels of sound pressure level” which is abbreviated “dB SPL”. We use a sound level meter to capture the amazing range of sound levels that humans can hear​ as shown on the sound thermometer below. ​​

We typically use the notation dBA to represent sound pressure levels that correspond to the sensitivity of the human ear, rather than dB SPL. ​