12-07-2012, 11:24 AM
voice recognition
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Introduction
Speech is the primary means of communication between people. For reasons ranging from technological curiosity about the mechanisms for mechanical realization of human speech capabilities, to the desire to automate simple tasks inherently requiring human-machine interactions, research in automatic speech recognition (and speech synthesis) by machine has attracted a great deal of attention over the past five decades. Designing a machine that understand human behavior, particularly the capability of speaking naturally and responding properly to spoken language, has intrigued engineers and scientists for centuries. Today speech technologies are commercially available for a limited but interesting range of tasks. These technologies enable machines to respond correctly and reliably to human voices, and provide useful and valuable services. Speech is processed through a non-contact method; you do not need to see or to touch the person to be able to recognize them. The popularity of speaker verification is swiftly growing because speech easy to obtain without the addition of dedicated hardware. Recognition systems can be broken down into two main types. Pattern Recognition systems compare patterns to known/trained patterns to determine a match and Acoustic Phonetic systems use knowledge of the human body (speech production, and hearing) to compare speech features (phonetics such as vowel sounds).
Project Background
The function of this voice recognition depends on the heart of the circuit is the HM2007 speech recognition integrated circuit. The chip provides the options of recognizing either forty .96 second words or twenty 1.92 second words. This circuit allows the user to choose either the .96 second word length (40 word vocabulary) or the 1.92 second word length (20 word vocabulary). For memory, the circuit uses an 8K X 8 static RAM. The chip has two operational modes; manual mode and CPU mode. The CPU mode is designed to allow the chip to work under a host computer. This is an attractive approach to speech recognition for computers because the speech recognition chip operates as a co-processor to the main CPU. The jobs of listening and recognition don’t occupying any of the computer's CPU time. When the HM2007 recognizes a command it can signal an interrupt to the host CPU and then relay the command code. The HM2007 chip can be cascaded to provide a larger word recognition library. The manual mode allows one to build a standalone speech recognition board that doesn't require a host computer and may be integrated into other devices to utilize speech control. Manual mode is preferred to be used since it can be apply at various type of appliance. The Interfacing type that selected to use is PIC Microcontroller -16F877A. Four output of home appliance will be connected are four lamp.
Project Statement
This project is develop in order to
• Control and command an appliance (computer, VCR, TV security system, etc.) by speaking to it, will make it easier, while increasing the efficiency and effectiveness of working with that device.
• Allows the user to perform parallel tasks, (i.e. hands and eyes are busy elsewhere) while continuing to work with the computer or appliance.
1.4 Objective To develop speech recognition system as a method for controlling To enhance previous technology in creative way To explore the new invention of technology in daily life application To control home appliance in easier way
Scope of Project /Limitation
Speech recognition is classified into two categories, speaker dependent and speaker independent. Speaker dependent systems are trained by the individual who will be using the system. These systems are capable of achieving a high command count and better than 95% accuracy for word recognition. The drawback to this approach is that the system only responds accurately only to the individual who trained the system. This is the most common approach employed in software for personal computers. Speaker independent is a system trained to respond to a word regardless of who speaks. Therefore the system must respond to a large variety of speech patterns, inflections and enunciation's of the target word. The command word count is usually lower than the speaker dependent however high accuracy can still be maintain within processing limits. Industrial requirements more often need speaker independent voice systems, such as the AT&T system used in the telephone systems.
Speech recognition systems have another constraint concerning the style of speech they can recognize. They are three styles of speech: isolated, connected and continuous. Isolated speech recognition systems can just handle words that are spoken separately. The user must pause between each word or command spoken. The speech recognition circuit is set up to identify isolated words of .96 second lengths.