Articulatory phonetics

In order for us to perceive stress differences, stress patterns must of course manifest themselves in the acoustic signal. How is this achieved Firstly, taking a contrast between normal syllables and their stressed version, we can say that, in the case of stress, the syllable is spoken with greater articulation effort, that is, the articulators are more likely to move to their canonical positions and, in so doing, produce a syllable with many of the idealised sounds which we would expect from our discussion of articulatory phonetics. As a by-product of this, we can see that the syllable seems more distinct in the spectrogram the formants of the vowel are clearly observable, and it is often easier to ascertain the identity of the vowel from the formants of stressed syllables than from unstressed ones. Likewise with the consonants, stops often have more distinct closure and burst patterns... 

In traditional phonetics, phones were seen as a set of distinct, discrete, separable units. This notion is no longer defensible as we now know that in reality the phonetic space is a multidimensional continuum (describable either with articulatory or acoustic dimensions), and there are no bottom up divisions within it. The concept of using phones should now be seen as an idealised division of phonetic space and this can be justifiable as a handy notational device it is cumbersome to describe every sound in terms of continuous dimensions (of say tongue height). It is important to realise however, that phones really are a discrete abstraction of a continuous space no procedure or process can be given for objectively defining these units. 

Praat, a system originally designed for phonetics research at the University of Amsterdam, comes with a remarkable physical model of the vocal tract, referred to as the articulatory synthesiser. The synthesiser is fully programmable, but we cannot change its architecture we can only write scores or tweak its parameters via a graphic user interface (GUI). A complete version of Praat is available on the CD-ROM. The functioning of the vocal tract is discussed below, followed by an introduction to the architecture of the synthesiser please also refer to Chapters 6 and 8 for more details. 

This section presents an introductory tutorial on how to control the physical model of the human vocal system that comes with the Praat system (Chapter 8). Praat was originally designed as a tool for research in the field of phonetics, but it features a sophisticated physical modelling vocal synthesiser (referred to as articulatory synthesis) that can produce vocal and vocal-like sounds of great interest to composers and sound artists. A brief introduction to the architecture of this synthesiser has been given in Chapter 4. In this section we will study how to control it. 

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