BEAVERTON, OREGON, May 22, 2018: Audio Precision announced today the upcoming release of APx audio measurement software version 4.6, with planned demonstrations at the 144th International AES Convention. Included in this latest edition of the popular test software will be the ability to perform measurements using the log-swept sine chirp—such as acoustic response—in an open-loop configuration, an enhancement ideally suited to the test and evaluation of smart devices (e.g., smart speakers, smartphones).

Closed-loop vs. Open-loop Audio Test
In a closed-loop test scenario, a known audio signal is generated by an audio analyzer and input into the device under test (DUT). With minimal or no delay, the output signal from the DUT is acquired by the analyzer and evaluated relative to the original signal to determine the DUT’s audio performance. For some DUTs, including smart devices, closed-loop testing isn’t feasible since either the known audio signal or the output signal may be a file, whether on the DUT or a server connected to the DUT. Such test setups—where the audio signal is not generated, passed through the DUT and analyzed in one continuous operation—are frequently referred to as open loop.

Log-swept Sine Chirp
The logarithmically-swept sine—also called chirp or continuous sweep—test signal has been an integral part of APx for over a decade and is based on the pioneering work of Professor Angelo Farina, a leading Italian theoretical and applied acoustician, of the University of Parma. The log-swept sine chirp is a brief, broadband stimulus signal that moves continuously across a specified range of frequencies (e.g., 20 Hz – 20 kHz) and is extremely advantageous in its ability to provide multiple high-resolution measurements—frequency response, harmonic distortion, rub and buzz—in a very short period.

“Open-loop chirp measurement capability is very important to developers of acoustic and electronic devices alike, especially engineers focused on smart device design, manufacture and evaluation,” said Dave Schmoldt, Audio Precision Chief Executive Officer. “Combining open-loop, time-selective (or quasi-anechoic) acoustic measurements with the performance, versatility, reliability and ease-of-use of the APx platform make for a very powerful audio test solution.”

APx software release version 4.6 will be available mid-Q3 of 2018. The release will be available as a courtesy download to registered users of and is compatible with all analyzers in the APx500 Series. Use of the open-loop chirp capability with APx515 analyzers requires at least one software option or bundle that contain a supported chirp measurement.

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