MODELLING AND EXTRACTION OF FUNDAMENTAL FREQUENCY IN SPEECH SIGNALS
Alipah Pawi · Brunel University Research Archive (BURA) (Brunel University London) · 2014
One of the most important parameters of speech is the fundamental frequency of vibration of voiced sounds.The audio sensation of the fundamental frequency is known as the pitch.Depending on the tonal/non-tonal category of language, the fundamental frequency conveys intonation, pragmatics and meaning.In addition the fundamental frequency and intonation carry speaker gender, age, identity, speaking style and emotional state.Accurate estimation of the fundamental frequency is critically important for functioning of speech processing applications such as speech coding, speech recognition, speech synthesis and voice morphing.This thesis makes contributions to the development of accurate pitch estimation research in three distinct ways: (1) an investigation of the impact of the window length on pitch estimation error, (2) an investigation of the use of the higher order moments and (3) an investigation of an analysis-synthesis method for selection of the best pitch value among N proposed candidates.Experimental evaluations show that the length of the speech window has a major impact on the accuracy of pitch estimation.Depending on the similarity criteria and the order of the statistical moment a window length of 37 to 80 ms gives the least error.In order to avoid excessive delay as a consequence of using a longer window, a method is proposed