Speech Recognition is the translation of spoken words into some text.it is known as ASR (automatic speech recognition), Computer Speech Recognition(CSR) or just Speech to text.Some speech recognition systems use Speaker-independent speech recognition while other use Training where an individual speaker reads section of text into the (SR) system.These system analyzes person specific voice and use it to fine tune the recognition of that person’s speech,resulting in more good transcription.System that do not use training are called”speaker-independent”systems.Systems that use training are called “Speaker-dependent”systems.
Speech Recognition application includes voice user interface such as voice dialling,call routing,domotic appliance control,search,simple data entry,preparation of structured documents and aircraft.
HISTORY OF SPEECH RECOGNITION
In 1932 Bell Labs researchers like harvey fletcher were investigating the science of speech perception.In 1952 three Bell Labs researchers built a system for single-speaker digit recognition.The 1950’s ERA Technology was limited to single-speaker system with vocabularies of around ten words.
(1)IN CAR SYSTEMS:Some of the most recent car models offer natural-language speech recognition in place of fixed set of commands allowing the driver to use full sentences and common phrases.With such systems there is no need for the user to memorize a set of fixed command words.
(2)HEALTH CARE::THERAPEUTIC USE:The use of speech recognition software in conjunction with word processors has shown benefits to short-term memory restrengthening in brain AVM patients who have been treated with resection.
(3)MILITARY::TRAINING AIR TRAFFIC CONTROLLERS:Many ATC training systems currently require a person to act as a “pseudo-pilot”,involving in voice dialog with the trainee controller,which affects the dialog that the controller would have to conduct with pilots in a real ATC situation.Speech recognition techniques offer the potential to eliminate the need for a person for act as a pseudo-pilot thus reducing the training and suport personnel.
(4)TELEPHONY AND OTHER DOMAINS:The improvement of mobile processor speeds made feasible the speech-enabled symbian and windows mobile smartphones. Speech is used mostly as part of user interface for creating predefined or custom speech commands.
(5)USAGE IN EDUCATION AND DAILY LIFE:Speech recognition can be useful for learning a second language.It can teach great pronunciation,in addition to help a person develop easyness with their speaking skills.Students who are blind or have very low vision can benefit from using the technology to convey words and then hear the computer recite them ,as well as use a computer by commanding with their voice,instead of having to look at screen and keyword.
DTW (DYNAMIC TIME WARPING) - SPEECH RECOGNITION.
Dynamic time warping is an approach that was historically used for speech recognition but has now largely been displaced by the more successful HMM-based approach.It is an algorithm for measuring similarity between two sequences that may vary in time or speed DTW has been applied to video and audio and graphics-indeed any data that can be turned into a linear representation can be analyzed with (dtw).