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. At the same time, we can work with other devices as a parallel tasks (i.e. hands and eyes are busy elsewhere).Readymade Chips are available in the market which can be used to embed with control circuits for recognition of devices.
On such circuit is the use of 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 doesn'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.
Some of Applications of this circuit:
• Command and control of appliances and equipment
• Telephone assistance systems
• Data entry
• Speech controlled toys
• Speech and voice recognition security systems
Currently most speech recognition systems available today are programs that use personal computers. The add on programs operate continuously in the background of the computers operating system (windows, OS/2, etc.). These programs require the computer to be equipped with a compatible sound card. The disadvantage in this approach is the necessity of a computer. While these speech programs are impressive, it is not economically viable for manufacturers to add full blown computer systems to control a washing machine or VCR. At best the programs add to the processing required of the computer's CPU. There is a noticeable slow down in the operation and function of the computer when voice recognition is enabled.
Courtesy: http://www.imagesco.com (article section)