Audio Precision Expands Channel Count for PDM Measurement

New module enables MEMS microphone array testing with simultaneous analysis of up to 16 PDM channels

BEAVERTON, OREGON, November 5, 2019: Audio Precision introduced today their PDM 16 module for the versatile APx500 Series audio analyzers. The new module offers simultaneous acquisition and measurement of up to 16 channels of PDM signals, making it the highest channel-count solution available for MEMS microphone and MEMS mic array testing.

APx PDM 16 Module, Remote Pod and cable with APx525 B Series Audio Analyzer

Audio Precision’s new PDM 16 module—shown here installed in an APx525 B Series audio analyzer and with its remote interface pod and cable—greatly expands the number of PDM test channels available to MEMS microphone array developers, enabling simultaneous analysis of up to 16 channels.

APx PDM 16 Module
PDM 16 is an optional interface module for the APx555, APx52x Series or APx58x Series audio analyzers. Comprised of the input module installed in the analyzer, a remote interface pod and an extension cable, the module provides sample-accurate inter-channel phase information, critical data for the creation of MEMS mic arrays. Developers of systems using beamforming microphone arrays and other DSP-based multichannel audio acquisition applications depend on a true representation of phase alignment of the input channels to validate their algorithms and designs. PDM 16 utilizes synchronous sampling based on a common clock, thereby assuring a clear picture of the phase relationship between channels.

With its acoustically-silent remote pod and extension cable preserving PDM signal integrity for up to 10 meters, PDM 16 readily supports microphone measurements in anechoic chambers. As an added feature, the module can provide up to 50 mA Vdd power supply to the device, or devices, under test.

MEMS Microphones
MEMS (micro-electromechanical system) microphones are extremely small microphones that are used in a wide range of applications and, most commonly, use a PDM (pulse density modulation) stream as their digital output. MEMS mics, either individually or in an array, are integral components in smartphones, hearing aids, mobile computing, automotive systems, smart speakers and other IOT systems.

Integrated Audio Test
As an APx module, PDM 16 is part of an integrated audio test solution, leveraging the combined power and flexibility of the APx500 audio measurement software and market-leading test hardware for signal generation and acquisition. Along with PDM 16, APx500 Series analyzers can include modules for testing components or systems that also use interfaces ranging from analog to chip-level I2S and TDM protocols, Bluetooth or HDMI. A PDM 16-equipped analyzer can even be equipped with the existing APx PDM module to add two channels of PDM output, as well as power supply rejection (PSR) and jitter measurements.

“With today’s smart devices incorporating as few as three and as many as seven MEMS microphones, the ability to conduct simultaneous, multichannel test is critical for developers in evaluating their designs,” stated Mike Flaherty, Audio Precision Chief Executive Officer. “Our PDM 16 module’s multichannel capability, acoustic test-friendly design, and ability to deliver sample-accurate inter-channel phase information make it the ideal measurement choice for MEMS mic designers and mic array developers alike.”

The APx PDM 16 module is available to order now, with shipment commencing mid-November 2019. When purchased with a new analyzer, PDM 16 retail pricing ranges from US $6,500 to $7,500, depending on the cable length option selected. Upgrades are also available for B Series or Legacy APx analyzers (in the latter case, for units manufactured after August 2012). PDM 16 requires APx500 audio measurement software version 5.0.3 or later. 

About Audio Precision
Audio Precision (AP) is a recognized world leader in electronic audio and electro-acoustic test instrumentation. Since 1984, AP’s analyzers have helped engineers to design and manufacture innovative solutions ranging from semiconductor devices to consumer, automotive, and professional audio products. For more information, visit

Visit the APx PDM 16 product page