sound pressure level is represented by the symbol spl, which is defined as taking the common logarithm of the ratio of the effective value of the sound pressure to be measured p(e) and the reference sound pressure p(ref), and then multiplying by 20, that is:

SPL=20LOG(10)[p(e)/p(ref)]

its unit is decibel (db).

the reference sound pressure p(ref) in the air is generally taken as 2*10e-5 pa. this value is the sound pressure value at which the normal human ear can just detect the existence of a 1 khz sound, which is also the audible threshold of a 1 khz sound. sound pressure. generally speaking, below this sound pressure value, the human ear can no longer detect the existence of this sound. obviously, the sound pressure level of the audible threshold sound pressure is zero decibels.

sound pressure level (spl):

sound pressure level (spl):
SPL ＝ 20log₁₀(P/P_ref)

spl = sound pressure level (spl)

p = sound pressure effective value

P_ref = reference sound pressure