Sound pressure level

Sound pressure level, also sometimes referred to as acoustic pressure level, measures the loudest sound that a device can record without distortion. Sound pressure level is denoted Lp and measured in dB.

To make measuring the sound pressure level easier, we use the decibel scale. The lowest sound pressure level of a device has a value of 0 dB, which denotes the human hearing threshold. The highest sound pressure level is known as the pain threshold (which means, as you can guess, that it begins to get painful to listen to sounds at this level) and has a value of about 120 dB. Most devices have a SPL that starts at about 20 dB.

Sound pressure level is an important measurement to understand if you’re comparing devices such as microphones. 

For example, the SPL for the Marantz MPM-1000U is 132, while the SPL for the Maono AU-902 is only 110. This means that the Marantz MPM-1000U can measure louder sounds than the Maono AU-902.

Unless you’re recording drums or other percussion instruments, SPL isn’t likely to be an issue for most microphones. This is because these types of instruments produce short peaks or higher frequencies that a microphone with a low SPL can’t pick up on to record clearly without distortion.