Presented by:- Nitin

Rawat TT-ET (0909533046)

INDEXObjectivesIntroductionDifference between speech and voice

recognitionThe logicStudy of components usedMethodologyChallenges faced and their solutionAdvantages and disadvantages

OBJECTIVESTo develop a speech recognition system

capable of recognizing the words spoken by

the user.

To make the system speaker independent.

Remove external noise using filters.

Retain data in RAM.

Remove external noise.

INTRODUCTIONSpeech is a natural mode of communication for people by

which they express their views and messages as voice utterances.

The electronic approach of speech recognition is to convert the speech into an electronic signal.

Analog representation of speech.

DIFFERENCE BETWEEN SPEECH AND VOICE RECOGNITION

Speech recognition Voice recognition

It is a speaker independent system.

The main function of this system is to recognize the word spoken by the speaker.

It concerns with what is being spoken and not who the speaker is.

It is a speaker dependent system

The main function of this system is to recognize the speaker first and then the words

It concerns with who is speaking and what is being spoken.

THE LOGIC

STUDY OF COMPONENTS USED The programming board

IC HM2007Single chip voice recognition CMOS. Speaker dependent. External RAM support. Maximum 40 word recognition (.96

second). Maximum word length 1.92 seconds

(20 word).Microphone support.Manual and CPU modes available.Response time less than 300

milliseconds. 5V power supply.

INTERNAL FUNCTIONS OF HM2007The chip provides the following error codes.

55 = word to long

66 = word to short

77 = no matchPressing “99” and then clear clears all the data inside the

RAM.

8k x 8 SRAMTTL-compatible inputs

and outputs.13 address pins8 I/O pins.Automatic power-down

when deselected.Static RAM organized

as 8192 words by 8 bits.

IC 74lS373Consists of eight latches

with 3-state outputs for bus

organized system applications.

D1-D8 are data inputs.Q1-Q8 are output pins.Used for controlling two

7 segment drivers.

IC 7448 (7 segment driver)Converts BCD data

into control signals for 7 segment display.

ABCD are the BCD inputs.

a-f are outputs for the 7 segment display.

7 SEGMENT DISPLAY

a-g are the connected to output of IC 7448.

Can display all hexadecimal digits from 0-9 and A-F.

METHODOLOGY

Data from RAM to latch

Speech input from mic

Trained words and codes fed in RAM

To & segment display or any other processing unit or interface.

• The IC HM2007 is the heart of this speech recognition circuit.

• The IC provides an analog front end, voice analysis, speech recognition and system control.

• The IC gets the analog signal from mic and converts it into digital codes.

• These codes are given specific notations or codes by the user and are stored in the RAM this is called as training.

• Now whenever the IC gets the same speech input it will give the same notation as given before.

CHALLENGES FACED AND THEIR SOLUTIONSExternal Noise reduction- it has been reduced by using a band pass

filter of range 300Hz - 3.1kHz .

•HomonymsHomonyms are words that sound alike. For instance the words cat, bat, sat and fat sound alike. Because of their like sounding nature they can confuse the speech recognition circuit.

•The Voice with Stress & ExcitementStress and excitement alters ones voice. This affects the accuracy of the circuit’s recognition. To achieve a higher accuracy word recognition one needs to mimic the excitement in ones voice when programming the circuit. These factors should be kept in mind to achieve the high accuracy possible from the circuit. This becomes increasingly important when the speech recognition circuit is taken out of the lab and put to work in the outside world.

ADVANTAGES AND DISADVANTAGESAdvantages• This technology is great boon for blind and handicapped as they can utilize

the voice recognition technology for their works. • As the speech recognition technology needs only voice and irrespective of

the language in which it is delivered it is recorded, due to this perspective this is helpful to be used in any language.

DRAWBACKS:• If the system has to work under noisy environments, background noise may

corrupt the original data and leads to SS misinterpretation. • If words that are pronounced similar for example, their, there, this

technology face difficulty in distinguishing them.

FUTURE SCOPENo typing by keyboard would be required as your voice will act as an interface between you and your computer

using speech for controlling various devices like car stereos,

GPS ,home appliances and various

other devices.

•Sub vocal speech recognition- The normal speech recognition can be extended to sub vocal speech recognition. This technology enables speech recognition through the vocal utterances. It is a boon to all the dumb people or people who face problems in speaking.