29. January 2020

Measurement of A2B Microphone Modules

A2B^* (abbreviation for Automotive Audio Bus) is a digital network technology from the Analog Devices Inc. company that connects the audio devices and components within a car. For example, the microphone modules, which are found in increasing numbers of modern vehicles since the advent of voice assistants, and which are connected to the car’s audio system via an A2B interface. In order to ensure reliable operation, these modules must be tested before installation.

A2B interface definition is proprietary. In order to be able to measure the microphone signals, a device is required that decodes the A2B data stream and converts it either into a digital AES/EBU or an analog signal. One such device is the A2B analyzer from Mentor Automotive.

NTi Audio FX100 Audio Analyzer with Mentor Automotive A2B Interface

The NTi Audio A2B Microphone Module Test System includes a Mentor Automotive A2B Analyzer. Together with the FX100 Audio Analyzer, it is possible to conveniently and reliably check all relevant acoustic parameters of the A2B microphones located on a module.

Typically, there are three or four digital MEMS microphones on an A2B microphone module. The dominant sound source in the car (the voice of the driver) can thus be localized and background noise reduced. For a complete function test of a module, it is essential to not only check the absolute parameters of the individual microphones, but also to determine their characteristics relative to each other. With little effort, this is achieved using the NTi Audio Microphone Test Software.