High quality digital audio

Suggests that in digital-audio systems aspiring to the description 'high-quality', an area of major importance is its accuracy in handling low-level signals. To some extent this focus reflects the author's direct experience designing and using digital audio components. The mechanisms of low-level distortions, both static and dynamic have been examined, as has the behaviour of some converter and DSP combinations. To assess the significance of noise and distortion products, auditory-band filtering was introduced, and the error of using 1/3oct filtering was examined. Setting typical replay levels for the system allows us estimation of the detectability of noise and other errors in the system. The author has proposed determining a quality measure based on the difference between the spectra TPD, triangular probability distributions, modulation noise and digital silence-where for a perfect chain all three curves would overlay. This raises some questions on the wisdom of using noise-shaped dither in real systems.<
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