Speech synthesis in

Speech synthesis

by Aveen M

Principles of speech synthesis

• Speech synthesis is a process which artificially produces speech for various application.

• Anybody can easily understand.

• Paper free.

Cont..

• First speech synthesizer is constructed in 1791.

• This synthesizer, capable of producing both vowels and consonants.

• Sounds originating through the vibration of reeds were modulated by the resonance of a leather tube and radiated as a speech wave.

• Able to produce 19 consonants and 5 vowels.

Mechanical speech synthesizer by von kempelen

Three speech synthesis methods

• Waveform coding.

• Analysis-synthesis.

• Synthesis by rule.

Synthesis based on waveform coding

• In which speech waves of recorded human voice stored after waveform coding are used to produce speech.

• Speech is synthesis by selecting and connecting the appropriate units.

• Store variations of the same words with rising, flat and falling inflections.

• Pitch synchronous method is used.

Time domain pitch synchronous overlap add

• The TD-PSOLA is a concatenation method.

• This method relies on the speech production model described by the sinusoidal framework.

• The analysis part consists of extracting short-time analysis signals by multiplying the speech waveform by a sequence of time-translated analysis windows.

• The analysis windows are located around glottal closure instants and their length is proportional to the local pitch period.

• Mapping specifies which of the short-time analysis signal will be eliminated.

Harmonic pulse noise model

• Spectrum is divided into two bands, with lowband being represented by harmonically.

• The noise part ,n(t) is obtained by filtering.

• Time-varying parameter referred to as maximum voiced frequency determines the limit.

• Synthesis time HNM frames are concatenated and the prosody of units is altered according to the desired prosody.

Thank you