Audio quality test to replace 'golden ear'

Audio quality test to replace ‘golden ear’
Steve Bush A new objective measurement for audio band quality will replace the need for ‘golden ear’ subjective tests, claims the International Telecommunication Union (ITU). The quality of audio material, both music and spoken, is notoriously difficult to test, especially if some form of compression scheme has been employed. Existing methods involve subtracting the original from the final signal and analysing the differences. This method works well for a near-linear system, but falls down badly if time delays (from transmission) or compression have occurred. “Audio compression systems like MPEG-1 and 2 shed 85 per cent of audio content, but sound exactly the same as the original material. They are clearly high quality, but traditional measurements rate them as very poor,” said Thomas Ryd?n who headed development of the new test at the ITU. This test takes into account the same psycho-acoustic response of the human ear that is exploited in compression. Quality is rated between 1.0 (awful) and 5.0 (no degradation) – an international standard. The range is heavily biased to high quality. “Most untrained people cannot tell apart systems in the range 3.5 to 5.0,” said Ryd?n. Those developing audio and voice codecs as well as broadcasters monitoring their output are expected customers. Tektronix, Rhode and Schwarz, Philips and Hewlett-Packard are said to be among those planning to incorporate the ITU test into their audio testing products.


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