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JOAN BAART, A field manual of acoustic phonetics. Dallas, TX: SIL International, 2010. Pp. 127. ISBN: 978-1-55671-232-6.

Published online by Cambridge University Press:  28 March 2011

Arkadiusz Rojczyk*
Affiliation:
University of Silesia, Polandarkadiusz.rojczyk@us.edu.pl
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Abstract

Type
Book Review
Copyright
Copyright © International Phonetic Association 2011

The information on the cover assures us that this book provides a practical and easy-to-understand introduction to acoustic speech analysis and assumes only a basic knowledge of articulatory phonetics. So far, so familiar, since most introductions to acoustic phonetics set themselves similar objectives. However, unlike many such publications, Joan Baart's book does what it promises.

What is most appealing in this book is conciseness and simplicity. It discusses basic concepts of acoustic phonetics ranging from reading speech waves to analyzing acoustic correlates of prosody in a content of only 119 pages. This is praiseworthy economy, considering the fact that many books on acoustic phonetics need only a few fewer pages for their introductory chapters. Simplicity is the book's other asset. Most previous introductions to acoustic phonetics discourage even the most ardent students by throwing up an array of mathematical equations and formulae. While of some interest to physicists, these will be of little value to novice researchers aiming to do some rudimentary analyses of speech. With the widespread availability of freeware that carries out most of the computations covertly, students of acoustic phonetics need not learn step-by-step calculations. Rather, they should know how to interpret linguistically the data they have collected, and Joan Baart understands this. He uses waveforms, spectra and spectrograms to meticulously explain what we can find in the signal in a manner that is easy to understand even for readers with very limited knowledge of phonetics. Baart's experience in linguistic fieldwork stands him in good stead: he concentrates largely on English but also discusses samples from languages in Pakistan.

The book is divided into five chapters. Chapter 1, which serves as an introduction, outlines the role of acoustic phonetics in linguistic research. It rightly warns the reader that ‘[a]coustic phonetics does not take the place of phonological analysis’ (p. 3). Rather, the acoustic data may help to establish or verify phonological patterns in a given language. Next, Baart mentions here and subsequently the key problem of the lack of one-to-one correlation between sound categories and acoustic properties with which they are associated. What I miss in this chapter is a section on sound recording – how one deals with problems such as microphone placement, metering, and noise reduction. Good quality recordings are a prerequisite for successful analysis and I believe that Baart, as an experienced researcher in field phonetics, would have a bag of tricks to share with the readers.

Chapter 2 deals with speech waves as represented in a waveform. Baart begins with time and amplitude and proceeds to describe four basic types of speech wave. Finally, he explains how to recognize major types of speech sounds and determine segment boundaries, aided by waveform displays. Especially useful to the novice are Baart's consistent guidelines for locating segment boundaries, which is indispensable for objective temporal measurements of segments. Considering the very considerable confusion due to different criteria of delimiting segmental boundaries reported in the phonetic literature, this section cannot be undervalued.

Chapter 3 is a central part of this book. It describes what sort of information can be obtained from spectrograms and spectra. Baart discusses both broad-band and narrow-band spectrograms even though the latter is rarely used in segmental analysis, and most of the speech analysis programs available currently use a broad-band option as default. However, for the sake of consistency, the coverage of both is justified. Next, he describes the spectrum. What I could not find here is a briefly characterized distinction between Linear Predictive Coding and Fast Fourier Transforms. Subsequent sections introduce periodicity, formants and anti-formants. The chapter ends with acoustic features of groups of speech sounds. When discussing vowels, Baart eplains how to extract formant frequencies and plot them on a vowel diagram. Although he warns that F1 and F2 may not necessarily reflect the articulatory dimension of height and frontness/backness and that other perception-based scales, such as bark scale, may be used, he does not explicitly say that comparisons between multiple speakers may be impossible using raw data. Perhaps it is regarded as too sophisticated at this stage, but in my opinion normalization procedures which allow one to filter out physiological variation are essential. The less careful reader may jump to an unwarranted conclusion that, for example, male vowels may be plotted against female vowels to draw linguistically valid conclusions. All those caveats notwithstanding, the chapter is well written and leads the reader through spectral analysis in lucid and friendly way.

Chapter 4 is concerned with voice and aspiration. It starts with inverse filtering of voice which, as Baart admits himself, ‘is not practical for fieldworkers’ (p. 79). The next section, deals with the spectral composition of different phonation types. This section will be particularly useful to those investigating languages where a particular mode of voice is functionally contrastive. The chapter ends with the many acoustic features associated with the voiced–voiceless distinction. What I like here is that it is not restricted to standard parameters such as VOT, vowel duration, closure duration and voicing in closure, but it also discusses F0 on a following vowel, energy of release burst or abruptness of formant transitions to a following vowel. It provides the reader with a soberingly realistic description of the potential complexity of the voicing contrast.

Chapter 5 deals with prosody. Baart wisely impresses on the reader that analyzing prosody is not simply reading fundamental frequency and intensity contours. Not only do speakers differ in individual F0 range but also different consonant types have their characteristic F0 peaks and rises. Moreover, various segments have intrinsic intensity. It is therefore especially important to devise test materials that will provide for this variability. The second part of this chapter is devoted to word stress or, using Baart's terminology, to accent. It describes a trading relation of properties such as duration, intensity, spectral tilt and, rather briefly, vowel reduction. The reader is advised to analyze stress using proportional rather than absolute values or use minimal pairs in order to avoid distorting influences of other factors unrelated to stress. The chapter ends with a rather too short section on intonation, a page-and-a-half long.

Summing up, it is worth repeating what was expressed at the beginning of this review. A field manual of acoustic phonetics is a practical and easy-to-understand book on basic concepts in acoustic analysis. It should be recommended to beginner students of speech acoustics because it interestingly provides discussion of rudiments of acoustic phonetics without daunting the reader with physical and mathematical aspects of the signal analysis. Even a limited number of references is a virtue rather than vice in a book like this. A book that combines an explanation of speech acoustics with a manual on how to operate one of the freeware speech analysis software packages that are commonly used in the acoustic research remains to be written.