Physical modelling synthesis of the human voice

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. 

Although Praat provides a graphic interface for the specification of the synthesiser s control parameters, all examples in this section will be given in the form of Praat scripts. A Praat script is a list of commands for Praat. The system comes with a useful and straightforward script editor for writing and running scripts and it is well documented in the user manual that is available via the program s Help menu. 

In many ways, a Praat script could be regarded as a score file in the style of a Music N type of synthesis programming language, as introduced in Chapter 1. The main difference is that one cannot build instruments in Praat. One can, however, change certain characteristics of the synthesiser in order to create different speakers. It is possible to customise the size of the vocal tract, the thickness of the vocal folds, the size of the nasal cavity, and so on. 

In order to s)mthesise a sound using the Praat physical model one needs to indicate (a) the speaker and (b) a list of actions. In Praat parlance, the speaker is referred to as the Speaker object and the list of actions is referred to as the Artwork object. In practice, a script contains instructions for an Artwork object and a call for a Speaker object that should be defined beforehand in a separate file. For the sake of simplicity, the following examples will employ PraaPs default adult female speaker model and we will refrain from changing its physical characteristics. 

In the following examples, the remaining 19 variables of the model are set to the default system values. These default values normally correspond to the resting positions of the respective parts that they represent. 

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