What Does SPL stand for and how is it measured?

Answer 1

SPL stands for Sound Pressure Level. It basically relates to how much acoustic energy is in sound that you hear. SPL is measured in decibels, or dB. The base reference for SPL is 0dB_SPL, which corresponds to a pressure of 0.0002 dynes per square centimeter, or about the quietest sound a young, undamaged ear can hear, between 1khz and 4khz. SPL of typical situations are: * quiet home at night = 50dB * average conversation = 65dB * heavy street traffic 5 feet away = 90dB * loud Rock Music at concert = 112dB (or more) * threshold of pain = 130dB * rifle fired 3 feet away = 140dB Some SPL trivia: * An increase of 3db in loudness is just barely perceived as a change, 10dB seems about twice a loud as before to human ears. * If you are playing sound (music, etc.) through an amplifier, and you double the output power by turning up the volume (say, from 20 watts to 40 delivered to the speaker), the SPL will go up about 6dB. * There are several different weighting schemes, the two most popular being A and C weighting, that (supposedly) modify the SPL curve to more closely fit the way our ears hear. "A" weighting is commonly used to measure noise, and test for sound that may damage ears. "C" weighting is commonly used to measure sound levels such as audio sound system output, listening rooms, concerts, and the like. * Pure SPL by itself does not really tell us how loud we will perceive a sound, since the human ear reacts differently to different frequencies, thus the reason for weighting curves. SPL is measured with, yup, an SPL meter. SPL, or 'Sound Level' meters, use a calibrated microphone and amplification to measure and display SPL on an analog meter or digital display.