Microphone Sensitivity

Microphone sensitivity expresses to how well a microphone converts sound pressure into an electrical signal . The sensitivity of a microphone is one of the most important parameters. It states how much output voltage the microphone delivers when exposed to a specified sound pressure. Microphone sensitivity is typically measured with a 1 kHz sine wave at a 94 dB sound pressure level (SPL), or 1 pascal (Pa) pressure.

 Due to the complexity of a microphone it is not just a linear realtionship between voltage, resitsor and output resistance.

The following diagramms give you an idea what you can expect in mic sensitivity for standard phantom power voltages using the associated feeding resistors. The input impedance is meant to the feeding resistor parallel to the input resistor.

 

Microphone sensitivty reduction as a function of input impedance. Input impedance is the feeding resistor in parallel to the AC coupled input resistor.

The following diagram shows the typical results of a CPX-1212 microphone having an open circuit sensitivty of 8.6mV.

 

  To make calculations easier, we have normalized the individual graphs to the open circuit sensitivity for each phantom power voltage