Model and filter circuit for modeling an acoustic sound channel, uses of the model, and speech synthesizer applying the model

A speech synthesizer, comprising

• input means;
• a microcomputer connected to said input means, said microcomputer having a temporary random access memory, a central processing unit and a permanent readout memory having a program stored therein, said central processing unit operating in a manner prescribed by said program stored in said permanent readout memory, said input device supplying to said microcomputer a coded text to be synthesized and said text passing through said input means in the form of series or parallel mode signals to said temporary memory of said microcomputer, said microcomputer reading said text and storing said text in said temporary memory, and after completion of the storing of the string of symbols to be synthesized, starting a control synthesis program which analyzes the stored text and sets up tables, and uses sets of rules to provide control signals;
• a pulse generator connected to said microcomputer;
• a noise generator connected to said pulse generator;
• an electronic filter system connected to said microcomputer, said pulse generator and said noise generator for modelling an acoustic sound channel, said pulse generator, said noise generator and said electronic filter system comprising a terminal analog, and said control signals provided by said microcomputer being supplied to said terminal analog, and said electronic filter system comprising electrical filter elements each having a rational transfer function approximating a partial transfer function Hij computed by decomposing the acoustic transfer function of a homogeneous sound channel ##EQU12## into n partial transfer functions Hij (i=1 . . . n,j=n+1 . . . 2n) comprising only the ith, (i+n)th, (i+2n)th . . . formant of H.sub.A, said filter elements having formant circuits, and connecting means connecting said formant circuits in a manner whereby formant circuits with formants mutually adjacent in frequency are in cascade with each other;
• and
• transducer means connected to said electronic filter system for converting electrical signals to acoustic signals.