The image on this slide is an example of a microphone frequency response curve. It shows the voltage in dB relative to 1 Vrms, for a sound pressure of 0.1 Pascal. The voltage output at 1 kHz is referred to as the sensitivity. Both reference sound pressures (1 Pascal and 0.1 Pascal) are in common usage; 1 Pascal sensitivity is 20 dB greater than 0.1 Pascal sensitivity.