Audio Precision takes the headache out of earphone testing  

5th August 2010

ES Admin

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Audio Precision, the recognized standard in audio test and measurement, has today produced a software utility that automates testing of headphones and earphones used with portable audio players. The utility, which runs exclusively on Audio Precision’s APx Series analyzers, automates the measurements required by British Standard / European Norm 50332 Parts 1 and 2.

The accompanying new AP Technote “Measuring the Sound Pressure Level of Portable Audio Player Headphones with APx Audio Analyzers” describes in detail how to use the utility to conduct the tests specified in the standard.

According to Audio Precision distributor Man Li of AP Technology in China, the new utility and its accompanying Technote will save manufacturers hundreds of hours of development time and “reduce the possibility of costly mistakes in their testing programs.”

The standard requires a special Program Simulation Noise test signal and a test fixture known as a Head and Torso Simulator (HATS). Sound pressure levels measured in the ear simulators of the HATS must be corrected to free field response and then A-weighted and averaged.

“The calculations needed to derive the results required by the standard are too complex for the typical user to do manually”, says Joe Begin, head of AP’s Technical Support. “And the Program Simulation Noise signal would also be a challenge for customers. We used Matlab™ to create the signal in the digital domain. The utility bundles that in and takes care of all the necessary calculations.”

The automated software utility was written for users of APx Series audio analyzers. APx is a next-generation platform with several models including the high performance APx525, the multichannel APx585 and the low cost APx515 optimized for production test. All APx models use the same software and feature one-click automation, award-winning UI, and automated reporting. Each APx analyzer comes with an ISO:17025 Accredited Calibration and three year warranty, so results are trusted everywhere.

The Technote can be downloaded at no charge from AP’s website;
http://ap.com/download/technotes.

For this Technote, AP used a KEMAR Manikin Type 45BA Head and Torso Simulator provided courtesy of G.R.A.S. Sound and Vibration.

Images available at: http://ap.com/images/audio.tst/2010/07/hats_apx.jpg
and http://ap.com/images/audio.tst/2010/07/hats_inside.jpg

About BS EN 50332
The British Standard / European Norm (BS EN) 50332 standard is intended to protect users of portable audio devices from exposure to excessive sound levels, and has been adopted by the 31 European CENELEC (European Committee for Electrotechnical Standardization) member countries.