Microphone measurements

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Microphone measurements

One of the benefits of using the combination of these two kits STEVAL-MKI126 and

STEVAL-MKI129 or STEVA-MKI155 is the measurement of the different models of the

microphone. In this section a brief description of the microphone evaluation will be given.

The equipment used to measure the main parameters of a microphone is listed as follows:



Interface boards APWlink or ST audio hub (STEVAL-CCA035V1 or STEVAL-MKI138Vx

respectively)



STSmartVoice board (STEVAL-MKI126Vx)



Coupon board of the MP34DT01 (STEVAL-MKI129V3)



Reference microphone (G.R.A.S. Type 46AE)



Generic loudspeaker



Audio precision (Model 2722)

Figure 3. Test setup

The test is done by performing a synchronous acquisition of a couple of microphones, the

first is the reference calibrated microphone, the second is the device under test (DUT). The

two microphones are placed face-to-face to minimize the sound pressure differences

between the membranes of the two devices.

The reference microphone is used, exploiting the known parameters, to find the reference in

the acoustic domain. Once the sound pressure level near the membranes of the

microphones has been set to 1 PA, then by performing a reading of the DUT amplitude, the

sensitivity is found. The reference microphone is also used to measure the DUT frequency

response through a comparison between their sensitivities across the audio band. Since the