Articulatory reference theory should play a leading role in the future studies of analysis and recognition of speech. Articulatory representation of speech involves acoustical, anatomical and neurophysiological descriptions. This paper describes two methods of transformation of vocal tract configurations into frequency spectrum as the bases of practical speech analysis on the anatomical level. The first one is the calculation based upon the solution of sound wave propagation through vocal tract with proper boundary conditions this one becomes, however, too complex to solve practically in case of nasal sounds which have a side branch produced by nasal coupling. Another one is the calculation due to the equivalent network analysis of vocal tract configuration and this one gives the values of formant and anti-formant frequencies which are in good agreement with the results of analysis in case of nasal consonants. A few examples of calculation of formant/anti-formant frequencies from given vocal tract configurations in case of vowels, consonants and nasal consonants have confirmed that these two methods provide feasible processes of speech analysis in terms of vocal tract configurations.
Synthesis of vowels by a digital computer program is described in this paper. The program is developed for the purpose of 1)evaluation of the speech parameter extraction processes based upon autocorrelation method, 2)study on the auditory perception of effects of time variation of speech parameters, and 3)developement of artificial speech source for evaluation of transmission line. The program has nine speech parameters, such as first three formant frequencies and their bandwidths etc. , which can be controled in any from of time function pre-set by control information. Conversational speech sound composed of five Japanese vowels was synthesized by the program and the synthesized speech waves sound not only highly intelligible but also quite natural. These experimental results proved that this program was useful for the practical purposes mentioned above in respect to both memory capacity and speed for the computer M-IB