# Sound Pressure Level Calculator

Sound Pressure Level measurement refers to a logarithmic measure of the effective sound pressure of a sound relative to a reference value. Sound Pressure is measured in decibels (dB). The commonly used "zero" reference sound pressure in air is 20 μPa RMS, which is usually considered the threshold of human hearing (at 1 kHz).

Table of Contents:

Formula

Sound Pressure Level:

**SPL = 20log _{10} (P/P_{ref})**

Sound Pressure:

**P = P _{ref} * 10 ^{SPL/20}**

Reference Pressure:

**P _{ref} = P / 10 ^{SPL/20}**

**Where,**

SPL = Sound Pressure Level,

P = Sound Pressure,

P_{ref} = Reference Pressure.

Sound pressure in air can be measured using a microphone, and in water using a hydrophone. The SI unit for sound pressure p is the pascal (symbol: Pa). Decibels measure the ratio of a given intensity I to the threshold of hearing intensity. This advanced online Sound Pressure Level Calculator is used to calculate the level of sound pressure.