Decibel SPL (re 20 µPa) (dB SPL)

Sound pressure level in air: 20 times the base-10 logarithm of the RMS sound pressure divided by the reference pressure of 20 µPa. 0 dB SPL is 20 µPa, about the quietest sound a young adult can hear.

What is a decibel SPL?

Symbol: dB SPL
Quantity: Sound Pressure Level (dB SPL)
Unit system: other
Definition: Sound pressure level in air: 20 times the base-10 logarithm of the RMS sound pressure divided by the reference pressure of 20 µPa. 0 dB SPL is 20 µPa, about the quietest sound a young adult can hear.
Exact: Yes, the value is exact by definition
Source: ISO 1683:2015, Acoustics: Preferred reference values for acoustical and vibratory levels

Common applications

Used for noise and loudness: a whisper is about 30 dB, conversation about 60 dB and a rock concert over 110 dB. Hearing damage becomes a risk with long exposure above about 85 dB(A).

Decibel SPL (re 20 µPa) in other sound pressure level (db spl) units

Pa = 0.00002 × 10^(dB SPL ÷ 20)Decibel SPL (re 20 µPa) to Pascal converter
mPa = 0.02 × 10^(dB SPL ÷ 20)Millipascal
µPa = 20 × 10^(dB SPL ÷ 20)Decibel SPL (re 20 µPa) to Micropascal converter
dB re 1 µPa = dB SPL + 26.02059991Decibel SPL (re 20 µPa) to Decibel re 1 µPa (underwater) converter

Decibel SPL (re 20 µPa) quick reference

Decibel SPL (re 20 µPa) in other units
Decibel SPL (re 20 µPa)	Pascal	Micropascal	Decibel re 1 µPa (underwater)
0 dB SPL	= 0.00002 Pa	= 20 µPa	≈ 26.02059991 dB re 1 µPa
10 dB SPL	≈ 0.0000632455532 Pa	≈ 63.2455532 µPa	≈ 36.02059991 dB re 1 µPa
20 dB SPL	= 0.0002 Pa	= 200 µPa	≈ 46.02059991 dB re 1 µPa
30 dB SPL	≈ 0.000632455532 Pa	≈ 632.455532 µPa	≈ 56.02059991 dB re 1 µPa
40 dB SPL	= 0.002 Pa	= 2000 µPa	≈ 66.02059991 dB re 1 µPa
50 dB SPL	≈ 0.00632455532 Pa	≈ 6324.55532 µPa	≈ 76.02059991 dB re 1 µPa