Recognition of fricatives in continuous speech using fuzzy logic
The automatic classification of English fricatives from continuous speech using fuzzy logic is discussed. Two algorithms that classify the fricatives into four and six classes, respectively, were developed. This classification is achieved by combining distinctive features that are described by fuzzy sets and their associated membership functions. The two algorithms are independent; one is used for speech bandlimited to 3.2 kHz and the other for speech bandlimited to 7.5 kHz. The results obtained with the algorithms were very promising, an overall recognition rate of 89.7% being achieved for the narrowband algorithm and 76.2% for the wideband algorithm. This compares favorably to the results of perception tests carried out under the same conditions, where an overall recognition rate of 74.5% was achieved with narrowband speech and 77.6% for wideband speech. The results indicate that contextual information plays an extremely important part in the recognition of fricatives.