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We often use decibels, a measure of sound pressure, to describe how loud something is – but loudness is caused by how we perceive sounds, and the two often don’t line up.

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To learn more about this topic, start your googling with these keywords:
– Decibels (dB): a unit used to measure changes in pressure or power.
– Loudness: the intensity with which a sound is perceived.
– Weighted decibels (dBA): decibels that try to take into account our sensitivity for different frequencies to better approximate loudness.
– Frequency: the rate at which something occurs. In the context of sound it usually means ‘sound waves per second’.
– Audible: perceptible for the human ear.
– High sound: a sound that has a high (fast) frequency
– Low sound: a sound that has a low (slow) frequency
– Resonance: When multiple things have a similar frequency they will tend to move together and amplify each other.
– Echolocation: Using sound to “see”. Bats use this to hunt in the dark.
– Equal loudness contours: Curves that show the sensitivity of the human ear along the frequency spectrum.

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