Speech processing is the process by which speech signals are interpreted, understood, and acted upon. It specifically refers to the processing of human speech by computerized systems, as in voice recognition software or voice-to-text programs. Speech processing is important to many fields for both theoretical and practical uses, ranging from voice activation and control in phones to development of functional artificial intelligence in computer science. Interpretation and production of coherent speech are both important in the processing of speech; some concerns do favor one over the other, however, as the application needs of speech processing are very diverse.
Speech recognition is one of the most important aspects of speech processing because the overall aim of processing speech is to comprehend and to act on spoken language. One commonly used application of speech recognition is simple speech-to-text conversion, which is used in many word processing programs. Many applications require much higher precision than is needed for speech-to-text conversion software, though. There is great interest, for example, in using speech recognition in military aircraft to reduce some pilot responsibility and strain. In order for precision and accuracy to be attained, it is necessary for the speaker to calibrate the recognition software to his own voice and style of speaking.
Speaker recognition, another element of speech recognition, is another highly important aspect of speech processing, though it is not yet as widely applied as general speech recognition. While speech recognition refers specifically to understanding what is said, speaker recognition is only concerned with who does the speaking. Validating the identity of the speaker can be an important security feature to prevent unauthorized access to or use of a computer system.
Another component of speech processing is voice recognition, which is essentially a combination of speech and speaker recognition. Voice recognition occurs when speech recognition programs process the speech of a known speaker; such programs can generally interpret the speech of a known speaker with much greater accuracy than that of a random speaker.
Another topic of study in the area of speech processing is voice analysis. Voice analysis differs from other topics in speech processing because it is not really concerned with the linguistic content of speech. It is primarily concerned with speech patterns and sounds. Voice analysis could be used to diagnose problems with the vocal cords or other organs related to speech by noting sounds that are indicative of disease or damage. Sound and stress patters could also be used to determine if an individual is telling the truth, though this use of voice analysis is highly controversial.