Contents
Application in real life
Some of the applications of speech communications in real life are Digital
transmission and storage of speech.
• Speech synthesis systems.
A computer voice response system is basically an all digital automatic service which responds with the desired information by voice commands of the speaker.• Speaker recognition systems
The acoustic speech wave form is converted to a written equivalent of the message information in order to preserve the features of the speech signal that are relevant to speaker identity .The area of speech recognition can be classified into two sub areas1. Speaker verification: For speaker verification, one’s identity is claimed by the user and the decision to accept or reject the claimed identity is taken by the verification system strictly.
2. Speaker identification: Speaker identification is to choose the speaker whose reference patterns are closest to the sample speech patterns. But the above systems can be affected by the following factors
o Type of speech
o Number of speakers
o Type of speakers
o Speaking environment
o Transmission system etc.
Apart from the above applications there are many more ideas of signals and systems involved in the area of speech processing like :
• Spectrograms
In order to design systems for transmitting speech we use spectrograms. Spectrogram is a visualization method or tool to look at frequency content of a signal .It is a plot of frequency-energy envelope versus time. From a spectrogram of a speech signal we can find the energy variation involved in the spectrum. Generally, a human speech contains energy between 0 to 5khz. Thus effective speech transmission systems can be designed with the help of spectrograms which can cope up with the signal’s energy variation and thereby enhancing the quality of the signal. For example, in telephone systems which act as band pass filters passing energy between 200hz to 3.2khz, it is difficult to distinguish few high frequency sounds due removal of high frequency energy.
Acknowledgement
We would like to thank Prof. V.M.Gadre for his motivation in doing this presentation.References
• “Digital processing of speech signals”by Lawrence R. Rabiner
Ronald W. Schafer
• “Signals and systems”
by Alan V. Oppenheim,
Alan S. Willsky
S. Hamid Nawab
• “Speech communications”
by O’Shaughnessy
• “Speech and audio signal processing”
by Ben Gold
Nelson Morgan
