Most of us probably don't give a lot of thought to our audio metering. After all, provided the signal occupies the appropriate part of the scale, what is there to worry about? There is, of course, a lot more to it than that. An understanding of the underlying technicalities of acoustics, electronics and psychoacoustics is paramount in interpreting the increasingly complex audio metering systems now being employed. Thankfully, there is an excellent book on the subject...
Audio Metering (Focal Press, ISBN 978‑0‑240‑81467‑4), written by Eddy Bøgh Brixen, was first published privately by DK‑Technologies a decade ago. The new revised and extended version is published by Focal Press, which will help ensure this excellent book is brought to the attention of a wider audience — especially the student market, where it should be required reading. This second edition retains the medium octavo format (that's A5 to you!) of the original, but increases the page count by nearly 20 percent to 264 pages, which are crammed with easily digestible explanations, illustrations and facts.
The first ten chapters cover basic acoustics, analogue and digital signals, the decibel, the hearing process, frequency and time weighting, and the determination of loudness. These establish a solid knowledge base from which to explore the requirements of metering and the most common meter types — including the VU and PPM.
A new chapter has been added here to cover the evolving and increasingly important topic of loudness metering, exploring commercial systems from Dorrough, Dolby and TC Electronic LM5 systems, as well as the ITU‑R BS.1771 and EBU R128 standards. The book continues logically with chapters on meter calibration, scale comparisons, and dynamic scales including the K‑System, before delving into polarity and phase meters, and stereo and surround signal distribution metering.
With two thirds of the book now under our belt, chapter 21 explores related industry standards and practices, such as test‑tone and alignment levels, track allocations, and the published requirements for mastering audio on different media. Subsequent chapters cover electrical and acoustic summation of audio signals, digital audio interfaces and interpretation of their channel status information, and where and how to connect metering in an audio system.
The remaining seven chapters explain specific measurement technologies including FFTs, spectral analysis, sound‑level meters, NR and NC curves (for sound isolation specifications) and the measurement of room acoustics. A comprehensive glossary and index complete the book.
Audio Metering is a rather constrictive title for this superb book, because the information it contains actually spans virtually every aspect of professional audio, with the exception of microphone placement (although the influence of various mic techniques on different metering displays is discussed). The text is easy to read, with copious diagrams, screen shots and tables throughout. Anyone involved with professional audio will find this book utterly indispensable. Hugh Robjohns
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