Audio Precision announced the addition of a speech intelligibility measurement option for APx500 audio test software based upon the ABC-MRT speech processing algorithm. Measuring speech intelligibility is an important capability for engineers designing and validating a wide range of communication systems, products and components, especially those related to public safety (e.g., police, fire, emergency) where it is critically important.
Importance of speech intelligibility
The purpose of communication systems is to transmit information via speech. As such, the intelligibility—or comprehensibility—of the transmitted speech is of utmost importance. One of the more precise definitions of intelligibility is the proportion of speech items (words and/or speech sounds) uttered by a talker, and sent via a communication system, that can be recognized by the listener.
Introduction to ABC-MRT
ABC-MRT, or Articulation-Band Correlation Modified Rhyme Test, was developed by the Institute for Telecommunication Sciences (ITS) of the United States National Telecommunications and Information Administration (NTIA). It follows the paradigm of the Modified Rhyme Test, a technique for assessing speech intelligibility that involves subjective assessment by human subjects as detailed in ANSI/ASA Standard S3.2. To eliminate the time, complexity, and expense of the traditional human subject-based methodology, it uses a form of automatic speech recognition (ASR) to conduct an automated measurement that is closely correlated—greater than 95 %—to a Modified Rhyme Test. An added benefit is its use of real speech (English only), allowing it to support the testing of systems that use noise suppression and/or codecs that only pass speech.
Integrated audio, electro-acoustic and intelligibility measurement
Using the ABC-MRT option allows developers to measure the speech intelligibility of their designs with the company’s instrumentation and use that same equipment for the rest of their audio and electro-acoustic test requirements. Once installed, the ABC-MRT measurement can be easily incorporated into any test sequence.
“For designers and developers needing perceptual audio test capabilities, whether measuring quality or intelligibility, AP offers a wide range of options,” said Dave Schmoldt, Audio Precision Chief Executive Officer. “From PESQ and POLQA quality measurements to STI, and now ABC-MRT, intelligibility measurements, APx can meet their needs for analog, digital, electro-acoustic and perceptual audio test.”