What is the measurement unit for sound pressure levels?

The measurement unit for sound pressure levels is the decibel (dB). Decibels provide a logarithmic scale that quantifies the intensity of sound, allowing for the comparison of different sound pressure levels in a way that reflects how humans perceive changes in loudness. A sound measured in decibels represents a ratio of that sound pressure to a reference sound pressure, typically set at 20 micropascals, which is considered the threshold of hearing for the average human ear.

Hertz is a unit that measures frequency, indicating how many cycles per second a sound wave has, but it does not provide information on how loud a sound is. Watts measure power, which can be related to sound but does not directly convey the level of sound pressure. RMS (Root Mean Square) values refer to a statistical measure used in various contexts to calculate the effective value of varying signals, including audio, but again, this is not a unit specifically used for measuring sound pressure levels. Thus, decibels are the appropriate and widely recognized unit for quantifying sound pressure levels in acoustics.