Microphone Test Software

Microphone production naturally has an error rate. Sorting out faulty devices at an early production stage is important to increase the overall yield, reduce waste material and optimize the quality of the manufactured goods. Important for a modern, state-of-the-art microphone test system are reproducibility, automation, speed and simplicity. The FX100 Audio Analyzer offers the microphone test solution.

Measurement Functions:

• Frequency response in-axis, off-axis
• Sensitivity
• Distortion
• Signal-to-noise ratio S/N
• Detection of audible imperfections
• Directivity, polar plot
• Polarity

The automated calibration (i.e. equalization of the reference speaker) is carried out with the NTi Audio measurement microphone M2010. Thereafter the smart “learn-mode” simplifies tolerance definition by feeding the system with a representative set of one or more “Golden Samples”. The flexible tolerance management automatically derives its tolerance Pass/Fail criteria. The system also supports up to five different quality clusters, which may be user-defined, such as “Excellent”, “OK”, “Acceptable”, “Class 3” and “Reject”. This allows the manufacturer to distinguish among quality classes.

System integration into existing production lines and the connection to host controllers is very simple. The extremely short test cycle time allows the microphone test system to easily cope with high volume production lines.

The patented measurement algorithms have been optimized for factory noise immunity. This maximizes production line yield and allows the same measurement tests used in R&D to be applied to the production floor. In the production mode the measurement results are compared with the defined tolerances. The individual results of each measured parameter are summarized into a class results pass/fail. The measurement may be triggered by

• Operator, using the keyboard
• Serial number barcode reader
• DIO Input (e.g. PLC trigger signal or foot switch)

The measurement results are shown on the PC-screen, indicated at the digital I/O Output (e.g. driving red/green lamps or bin-sorter) and directly logged into a Microsoft Excel report.

The polar plot analysis with the NTi Audio precision turntable complements the microphone measurement system to an all-in-one solution. The polar diagram displays the directional characteristic related to the measurement frequency of the microphone. For detailed analysis, the measurement angles can be set to a resolution of less than 1°.

The high-speed FX100 Audio Analyzer generates a series of fast sweep signals, covering the complete audio band of interest, and the turntable TT01 rotates the microphone to the configured angles between the sweeps. The measurement time can be halved by choosing the 180° mode, which mirrors the polar image. The polar plot graphics can be adjusted after the completed measurement, thus the microphone test system offers full flexibility for post-processing.