2. PREPARED BY MANOJ TALUKDAR MSC 4 TH SEM ROLL-NO 05 GUKC-2012 IN THE GUIDENCE OF DR. SANJIB KR KALITA

3. INTRODUCTION speech recognition systems are very useful and can be used for various processes. The degree of usefulness of these systems depends on what function we are trying to streamline through the available features of speech recognition systems. Some are very common and are used in our day to day lives and some of us do not even realize it. There are also more advanced, robust systems that are capable of some inconceivable things

4. Multilingual speech processing (MLSP) is a distinct field of research in speech and language Technology that combines many of the techniques developed for mono lingual systems with new approaches that address specific challenges of the multilingual domain. Multilingual speech processing (MLSP )

5. What is Speech processing? Speech processing is the study of speech signals and the processing methods of these signals. The signals are usually processed in a digital representation, so speech processing can be regarded as a special case of DSP, applied to speech signal.

6. Speech recognition, which deals with analysis of the linguistic content of a speech signal. Speaker recognition, where the aim is to recognize the identity of the speaker. Speech coding, a specialized form of data compression, is important in the telecommunication area. Speech processing categories:

7. Voice analysis for medical purposes, such as analysis of vocal loading and dysfunction of the vocal cords. Speech synthesis: the artificial synthesis of speech, which usually means computer-generated speech. Speech enhancement: enhancing the intelligibility and/or perceptual quality of a speech signal, like audio noise reduction for audio signal.

8. Speech Recognition Speech recognition is the ability of a machine or program to identify words and phrases in spoken language and convert them to a machine-readable format. Speech recognition applications include call routing, speech- to-text, voice dialing and voice search.

9. Some Basics Needed For Understanding Speech Recognition Technology: Utterance Speaker Dependence Vocabularies Accuract Training

10. Utterance An utterance is the vocalization (speaking) of a word or words that represent a single meaning to the computer. Utterances can be a single word, a few words, a sentence, or even multiple sentences.

11. Speaker Dependence Speaker dependent systems are designed around a specific speaker. They generally are more accurate for the correct speaker, but much less accurate for other speakers. They assume the speaker will speak in a consistent voice and tempo. Speaker independent systems are designed for a variety of speakers. Adaptive systems usually start as speaker independent systems and utilize training techniques to adapt to the speaker to increase their recognition accuracy.

12. Vocabularies Vocabularies (or dictionaries) are lists of words or utterances that can be recognized by the SR system. Generally, smaller vocabularies are easier for a computer to recognize, while larger vocabularies are more difficult. Unlike normal dictionaries, each entry doesn't have to be a single word. They can be as long as a sentence or two. Smaller vocabularies can have as few as 1 or 2 recognized utterances (e.g." Wake Up"), while very large vocabularies can have a hundred thousand or more

13. Accuract The ability of a recognizer can be examined by measuring its accuracy − or how well it recognizes utterances. This includes not only correctly identifying an utterance but also identifying if the spoken utterance is not in its vocabulary. Good ASR systems have an accuracy of 98% or more! The acceptable accuracy of a system really depends on the application.

14. Training Some speech recognizers have the ability to adapt to a speaker. When the system has this ability, it may allow training to take place. An ASR system is trained by having the speaker repeat standard or common phrases and adjusting its comparison algorithms to match that particular speaker. Training a recognizer usually improves its accuracy. Training can also be used by speakers that have difficulty speaking, or pronouncing certain words. As long as the speaker can consistently repeat an utterance, ASR systems with training should be able to adapt.

15. Types of Speech Recognition Isolated Words Connected Words Continuous Speech Spontaneous Speech Voice Verification/Identification

16. Isolated Words Isolated word recognizers usually require each utterance to have quiet (lack of an audio signal) on BOTH sides of the sample window. It doesn't mean that it accepts single words, but does require a single utterance at a time. Often, these systems have "Listen/Not Listen" states, where they require the speaker to wait between utterances (usually doing processing during the pauses). Isolated Utterance might be a better name for this class.

17. Connected Words Connect word systems (or more correctly 'connected utterances') are similar to Isolated words, but allow separate utterances to be 'run together' with a minimal pause between them. Voice Verification/Identification Some ASR systems have the ability to identify specific users. This document doesn't cover verification or security systems.

18. Spontaneous Speech There appears to be a variety of definitions for what spontaneous speech actually is. At a basic level, it can be thought of as speech that is natural sounding and not rehearsed. An ASR system with spontaneous speech ability should be able to handle a variety of natural speech features such as words being run together, "ums" and "ahs", and even slight stutters.

19. Continuous Speech Continuous recognition is the next step. Recognizers with continuous speech capabilities are some of the most difficult to create because they must utilize special methods to determine utterance boundaries. Continuous speech recognizers allow users to speak almost naturally, while the computer determines the content. Basically, it's computer dictation.

20. Features of Speech Recognition Systems There are so many features of speech recognition systems. This useful interface, allows users/callers to interface with a system that runs on voice commands. Basically, you would be either speaking on the phone with a system that processes commands when spoken to. There are also features of speech recognition systems that work with computers to allow a user to speak commands to the computer screen. Speaker recognition systems are different and commonly mistaken for speech recognition. Speaker recognition is a security system to allow users to gain access to computer systems. If the computer recognizes the user, by their speech, it gives access to the given system that is being protected

21. However, many people get these two things confused. Another name for speaker recognition is voice recognition. So, features of speech recognition systems are completely different and not related to security whatever Some of the benefits of speech recognition systems are: 1.Quicker input of data for processing 2.Easy for people who are handicapped and cannot use their limbs 3.Data entry with no need to type – just speak what you want typed 4.Multi-tasking through various application systems for simultaneous processing 5. Adaptable to any language

22. Some of the types and features of speech recognition systems are: Automatic voice dialing Content based voice commanded web searches Report and document preparation via spoken word On board navigation controls for airplanes and other crafts. Medical transcription via the features of speech recognition systems Automated phone systems for banking, ordering, and choosing services

23. The features of speech recognition systems are amazing. This new wave technology is also used by militaries of nations around the world. The features of speech of speech recognition systems in this case are: aircraft control, steering, and weapons engaging. This type of processing and entry will eventually replace the keyboard depending on what features of speech recognition systems software you need. With the additional production capabilities, anyone would be wasting time with processing if they did not consider using this technology.