There are several common methods used to evaluate the sensitivity of electret microphone elements. These include white noise testing, frequency response testing, SPL testing, vibration testing, and linearity testing.
1. White Noise Test
A white noise generator produces a uniformly distributed frequency signal. By inputting this signal into the microphone and recording the output voltage, the mic's responsiveness to different frequencies can be assessed.
2. Frequency Response Test
A signal generator outputs a range of specific frequencies. These are input into the microphone, and the output voltage is measured. By plotting the frequency vs. output voltage curve (frequency response curve), the mic's sensitivity across the spectrum can be visualized.
3. SPL (Sound Pressure Level) Test
Using an SPL meter, the microphone's output voltage is measured under various sound pressure levels. This test helps determine the mic's sensitivity and its effective output range under different sound intensities.
4. Vibration Test
A mechanical vibration source is brought into contact with the microphone to generate vibration signals. The output voltage is recorded to evaluate the mic's sensitivity and response speed to mechanical vibrations.
5. Linearity Test
Input signals of gradually increasing amplitude are applied, and the microphone's output voltage is measured. The difference between input and output is analyzed to assess linearity and dynamic range.
Note: For the most accurate and repeatable results, professional-grade testing instruments and setups should be used when measuring microphone sensitivity.
