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This presentation explores neural net algorithms for recognizing Serbo-Croatian vowels, following previous work on Thai phoneme recognition. It covers speech recognition, signal processing, vowel formants, and data used in the project. The focus is on applying Perceptron, Backpropagation, and Support Vector Machine algorithms for accurate recognition. The study aims to advance speech recognition technology and further explore speaker-independent recognition.
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Neural Net Algorithms for SC Vowel Recognition Presentation for EE645 Neural Networks and Learning Algorithms Spring 2003 Diana Stojanovic
Summary • Neural net algorithms applied to recognition of Serbo-Croatian vowels • Follows Thubthong & Kijsirkul (2001) paper on Thai phoneme recognition • Light background will be provided
Introduction • Speech recognition has many applications (PCs, cell phones, home appliance activation a la Dilbert etc.)
Introduction 2 • There are various algorithms for recognizing speech, some of which rely on the recognition of individual phonemes or sounds
Block diagram of speech recognition system For this project Signal Processing: segmentation, spectral analysis Speech Recognition: Individual vowel recognition Signal Processing Speech Recognition
Previous work • Thubthong & Kijsirkul (2001) tested multi-class Support Vector Machine (SVM) vs. Multilayer Perceptron (MLP) for recognition of Thai Vowels and tones • They claim superiority of SVM, while the recognition rate differs by 2-3% for comparably complex systems
About speech sounds • Speech sound is an acoustic wave • Speaker’s vocal tract shapes the spectrum of each sound • Spectrum depends on the speaker and on the property of the particular sound (for instance /u/), thus recognition in spectral domain is possible
Vowel Formants • Vowels can be recognized in spectral domain by the characteristic “lines” corresponding to their properties (backness, height, lip rounding etc.) • These “lines” –formants- occur at resonant frequencies of the vocal tract
Data Used in the Project Data collection and Properties • Type of speech: speaker dependent, accented syllables • 480 isolated words were recorded and digitized at 11 kHz • Vowels in accented position segmented manually • Vowel formants measured by PCQuirer
Sound Features Measured • Only first two formants were used for training the nets in order to reduce complexity • Based on the property of the SC sounds, the performance should not suffer from this low dimensionality
Perceptron,Backprop and Support Vector Machine • We learned about this throughout the semester . For details, please refer to the paper
What is next? • First, finish the SVM results • Examine fast, connected speech • Speaker independent recognition