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Accurate Sound Reproduction Using DSP

Book Review By Hugh Robjohns
Published August 2016

The power of digital signal processing affects every aspect of modern life, and is an integral part of almost every device we use. An example of that is the way in which DSP is also now being applied by several commercial loudspeaker manufacturers to correct or compensate for the inherent mechanical deficiencies of loudspeaker systems, and also of listening room acoustics. This is a leading-edge science, but one which Mitch Barnett has set out to explain in this Kindle e-book, which also helps guide interested readers towards developing their own DSP-based loudspeaker-correction systems.

Book Review: Accurate Sound Reproduction Using DSPBarnett’s aim in this book is to help the reader develop unique custom digital filters that correct the frequency and timing responses of the reader’s loudspeakers within their specific listening environment — whether that be for computer desktop speakers, a high-end audiophile stereo system, a multi-channel home-theatre setup, or even an in-car audio system.

Of course, achieving this goal requires some technical tools, many of which will probably already be available but some may still be required. In addition to a computer, a measurement microphone and an audio interface, the author relies heavily on two commercial software packages: Acourate DSP Audio Toolbox, and JRiver Media Centre. I should also point out that, as this e-book incorporates quite a lot of colour images and screen grabs to explain and illustrate the various measurements and procedures, a colour-capable Kindle reader is essential.

If printed out on A4 paper this book would fill 204 pages, and it is divided into six chapters starting with an overview explaining how a corrective FIR filter can be convoluted with the source music to achieve much more accurate sound reproduction at the listening position. It goes on to assess what is expected of accurate sound reproduction — the various critical parameters that will be measured and adjusted, and the ideal target values. Chapter 2 looks at the practicalities of using the measurement and filter development tools, while the next chapter explores the measurement parameters in much greater detail. Chapters 4 and 5 explore ever more sophisticated techniques of optimising the DSP filter design, including driver linearisation, developing digital crossovers and time-alignment, as well as more advanced measurement techniques.

For anyone with an interest in DSP technology and how it can be applied to improve the performance of real loudspeakers in real rooms, this is a fascinating and very affordable e-book. It is both well-written and comprehensively illustrated, and guides the reader step-by-step through the concepts, techniques, and practical implementations of both the science and art of loudspeaker correction. I found it a fascinating read and although I haven’t used it to develop my own corrective DSP processing (yet), I do feel I have a much better understanding of this field as a result.