Digital Audio Papers

The contents of some of these papers are available electronically in Adobe PDF format by following the links. The others are available through the Audio Engineering Society. If you have problems getting these papers then please contact papers@nanophon.com.

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96 kHz Digital Audio

The benefits of 96 kHz sampling rate formats for those who cannot hear above 20 kHz

Abstract: Reports that 96 kHz sampled digital audio systems have greater transparency than those sampling at 44.1 kHz apparently conflict with knowledge of the capability of human hearing. The band-limiting filters required are examined for a role in producing these differences. Possible mechanisms are presented for these filters to produce audible artefacts and filter designs avoiding these artefacts are illustrated
Julian Dunn - `The benefits of 96 kHz sampling rate formats for those who cannot hear above 20 kHz' Preprint 4734, presented at the 104th AES Convention, Amsterdam, May 1998.


Interfacing and Jitter

Considerations for Interfacing Digital Audio Equipment to the Standards AES3, AES5, AES11

Abstract: The implications of various parts of the digital audio interface are critically examined. Some specific design approaches are recommended for implementing the interface and some additional specifications are suggested for the system designer to consider.
Julian Dunn - `Considerations for Interfacing Digital Audio Equipment to the Standards AES3, AES5, AES11' Published in `Images of Audio', the Proceedings of the 10th International AES Conference, London, September 1991. pp 115-126.

Jitter: Specification And Assessment In Digital Audio Equipment

Abstract: Timing jitter in digital audio equipment can subtley degrade the audio quality or even cause data transmission failure. This paper examines the jitter performance requirements for digital audio equipment in the context of the audibility of sampling jitter modulation effects and the digital audio interface specification. It concludes by presenting techniques for the measurement of jitter performance.
Julian Dunn - `Jitter: Specification and Assessment in Digital Audio Equipment'. Preprint 3361, presented at the 93rd AES Convention, San Francisco, October 1992.

Towards Common Specifications for Digital Audio Interface Jitter

Abstract: An ad-hoc Task Group within the SC-2-2 (Digital Input/Output Interfacing) Working Group is developing a more detailed specification for jitter in the embedded clock of the digital audio interface signal. The discussion and the intermediate conclusions of this work are presented in this paper as an invitation for informal comment and debate about the issues raised.
Julian Dunn, Barry McKibben, Roger Taylor and Chris Travis - `Towards Common Specifications for Digital Audio Interface Jitter' Preprint 3705, presented at the 95th AES Convention, New York, October 1993.

The Diagnosis And Solution Of Jitter-Related Problems In Digital Audio Systems

Abstract: Timing jitter can cause the failure of a digital audio interface, or subtle degradation in the quality of an A-D or D-A conversion. This paper presents measurement techniques which can be used in the diagnosis and analysis of jitter-related problems, and gives examples of their application.
Julian Dunn and Ian Dennis - `The Diagnosis and Solution of Jitter-Related Problems in Digital Audio' Preprint 3868, presented at the 96th AES Convention, Amsterdam, February 1994.

Jitter and Digital Audio Performance Measurements

Abstract:It is well known that timing jitter in digital audio converters can subtly degrade performance. Unfortunately standard audio measurements are not very useful for assessing sensitivity to jitter. Mathematical formulae are derived to relate the modulation artifacts produced by sampling jitter with the jitter amplitude and frequency. The audibility of these modulation artifacts is considered in relation to the jitter spectral content. After examining the main sources of jitter in digital audio systems, measurement techniques appropriate to assessing the sensitivity to each source are described. Results of these measurements are shown for some digital audio products.
Julian Dunn - 'Jitter and Digital Audio Performance Measurements', Published in `Managing the Bit Budget', the Proceedings of the AES UK Conference, London, 16-17 May 1994.

Sample clock jitter and real-time audio over the IEEE1394 high performance serial bus

Abstract: The asynchronous clocks within the IEEE1394 high performance serial bus present challenges for sample timing recovery in conjunction with the transmission of digital audio. Moreover the systematic nature of the jitter produced means that prototype systems are unlikely to produce worst-case performance. This is analysed and, with jitter audibility models developed elsewhere, a sampling jitter attenuation requirement is estimated.
Julian Dunn – ‘Sample clock jitter and real-time audio over the IEEE1394 high performance serial bus.’ Preprint 4920, presented at the 106th AES Convention, Munich, May 1999

IEEE1394 and Sampling Jitter

Abstract: Timing fluctuations, or jitter, in clocks can degrade audio quality when the clocks are used in analogue to digital or digital to analogue conversion. The asynchronous clocks within the IEEE1394 high performance serial bus produce jitter. This may present challenges for low jitter sample clock recovery in conjunction with the transmission of digital audio using that bus and so the nature of this jitter requires investigation. Measurements of recovered clock jitter in a simple system are presented which confirm the results of a previous simulation of jitter generation mechanisms. Possible engineering solutions are discussed.
Julian Dunn - 'IEEE1394 and sampling jitter' Published in `Moving Audio', the Proceedings of the AES UK Conference, London, 8-9 May 2000. pp 47-62.


High Dynamic Range Digital Audio

High Dynamic Range Audio Applications for Digital Signal Processing

Abstract: Application of digital signal processing to audio is often limited by available converter technology and recorder datawidth to processes with controlled dynamic range. In digital mixing consoles some analogue gain control is normally required to achieve adequate performance for the input channel ADCs and digital multi-track recorders.
Julian Dunn - 'High Dynamic Range Audio Applications for Digital Signal Processing '. Preprint 3434, presented at the 93rd AES Convention, San Francisco, October 1992.


CD Differences

An Investigation Of The Sonic Differences Between Numerically Identical Compact Discs

Abstract: It has been observed that CD media apparently containing identical data can have varying subjective sound qualities on replay. It is difficult to suggest a theoretical basis for this. This paper describes an analytical study of a variety of CD media and players in an attempt to identify the differences and to isolate their causes. The research is still in progress.
Ian Dennis, Julian Dunn and Doug Carson—'An Investigation Of The Sonic Differences Between Numerically Identical Compact Discs’ Preprint 4399, presented at the 101st AES Convention, Los Angeles, November 1996.


Measurement Techniques for Digital Audio by Julian Dunn

In 2001 Audio Precision, a US audio test & measurement manufacturer, asked Julian to write a book on digital audio measurement. This book quickly became a definitive resource for design engineers working in the field of digital audio the world over. In his classic tradition, the book covered the subject material in sufficient depth to be valuable to advanced readers while presenting the information in a way that a novice could grasp the concepts. The book is in its second printing in English; a Japanese translation was published in February 2004.

Measurement Techniques for Digital Audio focuses on the measurement of digital audio signals, and examines in great detail both techniques used to evaluate the performance of the converters and the digital interface signal that carries the audio.