Microphone sensitivity conversion - microphone transfer factor mV/Pa to sensitivity dB re dB re 1 V/Pa or dyne/cm2 mV/Pa dB mic sensibility - Eberhard Sengpiel sengpielaudio checker
 
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• Microphone sensitivity and conversion •

1 − Sensitivity (new): dB re 1 V/Pa ← → Transfer factor: mV/Pa

International standards have established 1 Pascal (Pa) as 94 dBSPL.
This reference point is now accepted for specifying the sensitivity of microphones.
The μbar found in some non-European specifications refers to 74 dBSPL (20 dB less than 1 Pa) and
the sensitivity or the transfer factor is not expressed in the usual form of "mV/Pa" as open circuit voltage rating

Reference: 94 dBSPL ⇒ 1 pascal = 10 µbars = 10 dynes/cm2
Auditory threshold: 0 dBSPL ⇒ 0.00002 Pa = 0.0002 dyne/cm2

Fill out the respective box and click on the calculation button below. The sensitivity must be a negative dB value.

Sensitivity  dB re 1 V/Pa   |   Transfer factor  mV/Pa
      |      
↓   |   ↓
      |      
Transfer factor  mV/Pa   |   Sensitivity  dB re 1 V/Pa
      |    
1 pascal = 10 µbars = 10 dynes/cm2 and 1 µbar = 1 dyne/cm2 = 0.1 Pascal
1 mV/Pa = 0.1 mV/µbar or 1 mV/µbar = 10 mV/Pa and Pascal = Newton/m2

Calculation formulas: Sensitivity = 20 × log (Transfer factor) and Transfer factor = 10Sensitivity/20
Given is the Sensitivity in dB re 1 V/Pa and the Transfer factor in V/Pa. 1 mV = 0.001 volts.

Microphone sensitivity conversion - sengpielaudio

2 − Sensitivity (old): dB re 1 V/dyne/cm2 ← → Transfer factor: mV/Pa

Microphone firms in the USA are partly still using the old sensitivity of "dB re 1 V/dyne/cm2"
or "dB re 1 V/µbar" (74 dBSPL) and do not show the usual form "mV/Pa".

Reference: 74 dBSPL ⇒ 1 dyne/cm2 = 0.1 pascal = 1 µbar
Auditory threshold: 0 dBSPL ⇒ 0.0002 dyne/cm2 = 0.00002 Pa

Fill out the respective box and click the 'calculate' bar below. The sensitivity must be a negative dB value.

Sensitivity  dB re 1 V/dyne/cm²   |   Transfer factor  mV/Pa
      |      
↓   |   ↓
      |      
Transfer factor  mV/Pa   |   Sensitivity  dB re 1 V/dyne/cm²
      |    

1 µbar = 1 dyne/cm2 = 0.1 Pascal and 1 pascal = 10 µbars = 10 dynes/cm2
1 mV/µbar or 1 mV/Pa = 0.1 mV/µbar = 10 mV/Pa and Pascal = Newton/m2

Pascal is written in English with lower-case letter beginning: We have the pascal and we
have the dyne, and the plural dynes which are microbars. A typical condenser microphone,
having 10 mV/Pa is the same as 1.0 mV/µbar; but 10 Pa are 100 µbar.
−40 dB "re 1V/Pa" equals to −60 dB "re 1V/microbar". There is a difference of 20 dB.

All field quantities, like the voltage, or the sound pressure
are always RMS values, if not otherwise stated.

Note

Forget the power ratings. They have no relevance to microphones. The term "dB SPL" is a measurement
of Sound "Pressure" Level (SPL) which is the force per area that acoustical sound waves apply to air
particles. Microphones are sensors in the sound field which deliver an analogous voltage. Microphones
measure sound pressure, or sometimes they may measure the particle velocity, but they never measure
sound intensity directly. Intensity stereo is an unfortunate linguistic misnomer which has come to mean the
recording of stereophonic signals that are distinguished only by level differences. In stereo the level
differences have been called "intensity" differences, but sound intensity is a specifically defined quantity
and cannot be sensed by a simple microphone, nor would it be valuable in music recording if it could
"Intensity" stereophony is a misnomer and is better called level difference stereophony. Ears are
directly only sensitive to sound pressure, like microphones. Forget both intensity and the power.
A studio microphone is never attached to a load equal to its own internal resistance. The load
resistor (impedance) should always to be at least ten times greater than the internal source
resistor of the microphone (open circuit). Here only voltage is important and not the power.

Notice: The output voltage of a microphone is proportional to the incident sound pressure.

To obtain the microphone maximum output level in dBu, find your microphone's sensitivity rating on
the left side and then move right until you are directly below your microphone's maximum SPL rating.
As an example, for a microphone with a sensitivity rating of 20 mV/Pa and a max SPL equal to 130 dB.

Table 1 tells us that the maximum output voltage is +4 dBu. You now have what you need to compare
preamps regarding maximum input level.

Maximum Output Level

Microphone Dynamic Range Calculation

Enter any TWO of the following values, then press the calculate button.
The missing value will be calculated.
The 10 μbar = 1 pascal ≡ 94 dBSPL rating is used here.

Max. SPL, e.g. 138 = dB SPL
Self noise, e.g. 16 = dB
Dynamic range = dB
     
            ↓
     
 S/N ratio re 94 dB SPL = dB

Self-noise may be entered using any weighting factor (A, CCIR 468 etc)
but the dynamic range will be predicated by that weighting.
"S/N re 94 dB SPL" is 94 dB minus self noise.
The max. SPL for less than 0.5 % THD should be used. If you find there values
for 1 % THD, then do a 6 dB subtraction, for a more correct comparison.

Note: There is no conversion formula for measured dBA values to sound pressure level dBSPL or vice versa.

Transfer factor:
mV/Pa (1 mV = 0.001 V)		  ↔  Sensitivity Europe + Intern.:
dB re 1V/Pa
Transfer factor = 10Sensitivity / 20
Sensitivity in dB re 1 volt per pascal		   Sensitivity = 20×log(Transfer factor)
Transferfactor in volts per pascal
Reference 94 dB-SPL ⇒ 1 Pascal      1 000 mV/Pa ≡ 0 dB

The sensitivity must be a negative dB value.

Transfer factor:
mV/Pa		  ↔  Sensitivity USA (old):
dB re 1 dyn/cm²
 
 		   This number shows 20 dB "more"
than Europe.
Reference 74 dB-SPL ⇒ 1 dyn/cm²      10 000 mV/Pa ≡ 0 dB

The sometimes found microphone "power level" in dB is wrong. It really means "sensitivity in dB re 1 V/Pa".

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