A new method for identifying voiced and unvoiced speech region is proposed. Voiced/unvoiced speech detection is needed to extract information from the speech signal and it is important in the area of speech analysis. Voiced and unvoiced speech region has been identified using Short Term Processing (STP) in this paper. Short Term Processing of speech has been performed by viewing the speech signal in frames, which has a size of 10-30ms. Short Term Processing has been performed in both time domain and frequency domain. Short Term Energy (STE), Short Term Zero Crossing Rate (STZCR) and Short Term Autocorrelation (STA) are computed from the time domain processing of speech. The spectral components in the speech signal are not apparent in the time domain. Hence, frequency domain representation is needed which is achieved using fourier transform. Conventional fourier representation is inadequate to provide information about the time varying nature of spectral components present in speech. So, short term version of fourier transform is needed, which is named as Short Term Fourier Transform (STFT).

1. A. E. Mahdi and E. Jafer, "Two-Feature Voiced/Unvoiced Classifier Using Wavelet Transform", The Open Electrical and Electronic Engineering Journal, No. 2, pp. 8-13, 2008.
2. Bishnu S. Atal and Lawrence R. Rabiner, "A Pattern Recognition Approach to Voiced-Unvoiced-Silence Classification with Applications to Speech Recognition", IEEE Transactions on Acoustics, Speech and Signal Processing, Vol. 24, No. 3, 2003, pp. 201-212.
3. D. G. Childers, M. Hahn and J. N. Larar "Silent and Voiced/Unvoiced/Mixed Excitation (Four-way) Classification of Speech", IEEE Transactions on Acoustics, Speech and Signal Processing, Vol. 37, No. 11, November 1989.
4. Lawrence R. Rabiner and Ronald W. Schafer, "Introduction to Digital Speech Processing", Foundations and Trends in Signal Processing, Vol. 1, No. 33-53, 2007.
5. Mojtaba Radmard, Mahdi Hadavi and Mohammad Mahdi Nayebi, "A New Method of Voiced/Unvoiced Classification Based on Clustering", Journal of Signal and Information Processing, 2011, Vol. 2, pp. 336-347.
6. N. Dhananjaya and B. Yegnanarayana, "Voiced/ Non-voiced Detection Based on Robustness of Voiced Epochs", IEEE Signal Processing Letters, Vol. 17, No. 3, March 2010.
7. R. G. Bachu, S. Kopparthi, B. Adapa and B. D. Barkana, "Voiced/Unvoiced Decision for Speech Signals Based on Zero-Crossing Rate and Energy", Advanced Techniques in Computing Sciences and Software Engineering, pp. 279-282, 2010.
8. Ronald W. Schafer and Lawrence R. Rabiner, "Digital Representations of Speech Signals", Proceedings of the IEEE, Vol. 63, No. 4, April 1975.
9. S. Ahmadi and A. S. Spanias, "Cepstrum Based Pitch Detection Using a New Statistical V/UV Classification Algorithm", IEEE Transactions on Speech and audio Processing, Vol. 7, No. 3, pp. 333-338, 2002.
10. Yingyong Qi and Bobby R. Hunt, "Voiced-Unvoiced- Silence Classifications of Speech Using Hybrid Features and a Network Classifier", IEEE Transactions on Speech and Audio Processing, Vol. 1, No. 2, pp. 250-255, 2002.

Voiced Speech Unvoiced Speech Short Term Energy Short Term Zero Crossing Rate Short Term Autocorrelation Short Term Fourier Transform.