Formants configuration

Hgure 13.2 Formant configurations (a) cascade or serial configuration and (b) parallel configuration. 

The two configurations are shown in Figure 13.2. Note that the parallel configuration has an amplitude (gain) control for each formant. 

Figure 13.3 The complete Klatt synthesiser. The boxes Rl, R2 etc. correspond to resonators generating formants. The A boxes control amplitudes at those points. The diagram shows both the serial and the parallel configurations of the formants.

The final further issue concerns the specification-to-parameters problem. In going from formant synthesis to LP synthesis the key move was to abandon an explicit specification-to-parameters model of vocal-tract configurations and instead measure the required parameters from data. From this we can use at synthesis time a lookup table that simply lists the parameters for each unit (typically a diphone). The cost in doing so is firstly that we lose explicit control of the phenomenon and secondly of course that we incur significant extra storage costs. If we now, however, look at how closely the LP parameters for one diphone follow parameters for lots of examples of that same diphone in many different real situations, we see that in fact even this purely data-driven approach is severely lacking, and in many cases the set of parameters for our diphone will match... 

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