lesson
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Plug the wrong microphone into a preamp, and a quiet vocal recording can end up drowning in hiss, while a snare drum track can clip into harsh distortion before reaching the mixer.
Microphone specification sheets provide the exact measurements needed to avoid these problems by defining how a mic handles signal level, background noise, and extreme volume.
How do we measure exactly how loud an electrical signal a microphone creates from incoming acoustic sound?
Sensitivity (mV/Pa and dBV)
Microphone sensitivity measures the electrical output voltage produced when a standard acoustic pressure is applied to the diaphragm.
The international standard test tone is a 1 kHz sine wave at a sound pressure of 1 Pascal (abbreviated Pa), which equals exactly 94 dB SPL.
📊Interactive diagram
Dynamic microphones typically produce around 1 to 3 mV/Pa (−60 to −50 dBV), meaning they have low sensitivity and require significant preamp gain.
Condenser microphones contain active internal impedance converters, producing higher sensitivity ratings around 10 to 30 mV/Pa (−40 to −30 dBV).
Because sensitivity tells you the output voltage, sensitivity in decibels relative to 1 Volt (dBV) is calculated using the formula: Sensitivity (dBV)=20log10(1 VVout)
Higher sensitivity is ideal for quiet, distant acoustic sources, but what happens when the room is completely silent?
Self-Noise / Equivalent Noise Level (dBA)
Self-noise (or equivalent noise level) is the electrical hiss generated by the microphone's own internal circuitry and thermal molecular motion, expressed as an equivalent acoustic sound pressure in decibels.