Formant synthesis sound sources

Beyond this the similarities between the formant s mthesiser and LP model start to diverge. Firstly, with the LP model, we use a single all-pole transfer function for all sounds. In the formant model, there are separate transfer functions in the formant synthesiser for the oral and nasal cavity. In addition a further separate resonator is used in formant synthesis to create a voiced source signal from the impulse train in the LP model the filter that does this is included in the all-pole filter. Hence the formant synthesiser is fundamentally more modular in that it separates these components. This lack of modularity in the LP model adds to the difficulty in providing physical interpretations to the coefficients. 

In terms of production, it is very similar to formant synthesis with regard to the source and vowels. It differs in that all sounds are generated by an all-pole filter, whereas parallel filters are common in formant synthesis. 

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