PAMS - A Perceptual Analysis/Measurement System
Determining the subjective speech quality of
a transmission system has always been an expensive and laborious process.
Now PAMS will provide a rapid and repeatable result in a few moments
across any network, even those subject to packet loss or variations
in delay.
The PAMS process uses an auditory model that combines
a mathematical description of the psychophysical properties of human
hearing with a technique that performs a perceptually relevant analysis
taking into account the subjectivity of the errors in the received
signal. The PAMS process compares the original and received signal
and determines Mean Opinion Score predictions, on a scale of 1-5, for
the listening quality and listening effort. The score calculated by
PAMS will be within one half of typical MOS determined by a controlled
subjective test in a laboratory.
The PAMS model has been validated on an extensive
database of subjective tests employing human subjects across a variety
of speech carrier technologies. This robust algorithm has been verified
against subjective test results of low bit-rate codecs, packet switched
techniques and various bandwidth compression devices. It is robust
for Voice over I/P applications.
The performance of a network or a network element
can be fully characterised using the Digital Speech Level Analyser
and PAMS. Whilst it is possible to use phonetically balanced sentences
and other test patterns, accurate and repeatable measurements of the
active speech level, activity, delay, echo, noise and speech quality
can be obtained quickly using the artificial speech test stimulus in
different languages. A graphical mapping of the errors provides a useful
insight into how the signal has been degraded.
This powerful test tool can be deployed in many different areas of a business, on any speech carrier technology:-
- In the research laboratory; providing rapid feedback
on promising areas of signal processing development, validation of
design implementation, ranking alternative design solutions, providing
a higher degree of confidence before submission to subjective testing
- In network equipment evaluation; comparing different
vendor offerings and determining their impact on network performance
- In network installation and rollout of new technologies;
ensuring that the desired speech quality is being delivered as the
network complexity and loading increases
- In troubleshooting network and customer problems;
determining the scale of the problem, the effectiveness of the solution
- In sales and marketing; demonstrating the excellence
of a new product, assuring the customer of the system performance
Malden Electronics is committed to the development
of cost effective tools to measure all aspects of speech transmission.
The integration of the Perceptual Analysis/Measurement System into
the Digital Speech Level Analyser represents another breakthrough in
speech quality measurement technology.
© Copyright Malden Electronics Ltd 1998.
This software has been verified to be a valid implementation of the
Perceptual Analysis/Measurement System (PAMS) developed by British Telecommunications plc.
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