Reference value (acoustics)

Reference value denotes special values that are used when specifying levels for physical quantities commonly used in acoustics . A separate reference value is defined for each of these variables. The level specification 0 dB means that the size value is the same as the reference value.

The best-known reference value is the value of 20 µPa determined based on the hearing threshold for calculating the sound pressure level .

Important standardized reference values for the calculation in acoustics are:

level	Reference value
Sound pressure level L _p	${\ displaystyle p_ {0} = 2 \ cdot 10 ^ {- 5} \, \ mathrm {Pa}}$ = 20 µPa (in air) ${\ displaystyle p_ {0} = 10 ^ {- 6} \, \ mathrm {Pa}}$ = 1 µPa (in other media)
Deflection level L _ξ	${\ displaystyle \ xi _ {0} = 10 ^ {- 6} \, \ mathrm {m}}$ (Structure-borne noise)
Sound velocity level L _v	${\ displaystyle v_ {0} = 5 \ cdot 10 ^ {- 8} \, \ mathrm {m} / \ mathrm {s}}$ (Airborne and structure-borne noise) ${\ displaystyle v_ {0} = 10 ^ {- 9} \, \ mathrm {m} / \ mathrm {s}}$ (mainly water-borne noise)
Acceleration sound level L _a	${\ displaystyle a_ {0} = 10 ^ {- 6} \, \ mathrm {m} / \ mathrm {s} ^ {2}}$ (Structure-borne noise)
Sound power level L _W	${\ displaystyle P_ {0} = 10 ^ {- 12} \, \ mathrm {W}}$
Sound intensity level L _I	${\ displaystyle I_ {0} = 10 ^ {- 12} \, \ mathrm {W} / \ mathrm {m} ^ {2}}$
Sound energy density level L _w	${\ displaystyle w_ {0} = 10 ^ {- 12} \, \ mathrm {J} / \ mathrm {m} ^ {3}}$
Sound energy level L _E	${\ displaystyle E_ {0} = 10 ^ {- 12} \, \ mathrm {J}}$