an A
The loudness of sound is measured using the "decibel" or "bel" unit.
The unit for amplitude is the same as the quantity being measured. For example, for sound waves, the unit could be decibels (dB). There is no specific symbol for amplitude as it depends on the context, but it is often represented by "A" or "Α".
using unit newton with symbol N
sound is measured in decibles
The decibel.
Decibels (dB)
If you mean the pitch of a sound, that is related to its frequency. The SI unit is the Hertz.
The base unit for length is the meter, and the symbol for meter is "m."
The unit for measuring the volume of sound is the decibel.
The volume of a sound is measured by the sound pressure in pascals or newtons per square meter. The sound pressure level is measured by a sound pressure level meter (SPL meter).
That is commonly measured in decibels.