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Monday, 25 June 2012

HM2007...Simplest Hardware for speech Processing

                           Hi.......We all are use many risky programs for speech processing . Here is simple solution for this.We can done speech processing like a toy by using HM2007 processor and its training kit.There is no need to program.HM2007 is a single chip CMOS voice recognition LSI circuit with the on-chip analog front end,voice analysis,recognition process and system control functions.A 40 isolated-word voice recognition system can be composed of external microphone,keyboard,64K SRAM and some other components.Combining it with microcontroller we build an intelligent recognition system. 

The figure below shows the speech training circuit using HM2007

  •  Single chip voice recognition CMOS LSI
  •  Speaker -dependent isolated word recognition system
  •  External SRAM can be connected directly
  •  Maximum 40 words can be recognized for one chip
  •  Maximum 1.92 sec of word can be recognized
  •  Multiple chip configuration is possible
  •  A microphone can be connected directly.
  •  Response time is less than 300ns
  •  5v single power supply

                          Speech recognition is the process of converting an acoustic signal,captured by micro- phone or a telephone, to a recognized command or word. There two important part of in Speech Recognition - i) Recognize the series of sound and ii) Identified the word from the sound. This recognition technique depends also on many parameters -Speaking Mode, Speaking Style, Speaker Enrollment, Size of the Vocabulary, LanguageModel, Perplexity, Transducer etc. There are two types of Speak Mode for speechrecognition system - one word at a time (isolated-word speech) and continuous speech.Depending on the speaker environmental, the speech recognition system can also divide -Speaker dependent and Speaker independent system.The most popular and dominated technique in last two decade is Hidden Markov Models. There are other techniques also use for SR system – Artificial Neural Network (ANN), Back Propagation Algorithm (BPA), Fast Fourier Transform (FFT), Learn Vector Quantization (LVQ), Neural Network (NN).


                              Currently, most speech recognition systems available today are programs that use personal computers equipped with a sound card. These memory-resident programs operate continuously in the background of the computers operating system (Windows, OS/2, etc.), allowing the speech recognition program to be used with other programs like Word or Excel. There is a noticeable slow-down in the operation and function of the computer when the memory resident voice recognition program is enabled. The memory resident programs add to the processing overhead of the computer's CPU. From a commercial aspect, the disadvantage in this approach is the necessity of a computer.


                     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 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 maintained within processing limits.


                         The HM 2007 has an inbuilt hardwired Artificial Neural Network
system. For each time the user says the word, the HM2007 integrates this word into a neural network. Later, in recognition mode, the HM2007 tries to match the spoken word against other words in its neural net. If a match is made, the index of that word in the vocabulary is returned. If no match is found, or if the user spoke too quickly or too slowly, an appropriate error code is returned.
Training Words for Recognition
                         Press “1” (display will show “01” and the LED will turn off) on the keypad,then press the TRAIN key ( the LED will turn on) to place circuit in training mode, for word 'left'. Say the target word into the on microphone clearly. The circuit signals acceptance of the voice input by blinking the LED off then on. The word (or utterance) is now identified as the “01” word. If the LED did not flash, start over by pressing “1” and then “TRAIN” key. You may continue training new words in the circuit. Press “2” then TRN to train the second word and so on. The circuit will accept and recognize up to 20 words (numbers 1 through 20)

Testing Recognition
                    Repeat a trained word into the microphone. The number of the word should be displayed on the digital display. For instance, if the word “left” was trained as word number 20, saying the word “left” into the microphone will cause the number 20 to be displayed.
The chip provides the following error codes.
55 = word to long
66 = word to short
77 = no match


  1. hello!
    The HM2007 IC, does it need to be programmed seperately to connect as shown in the circuit above are does it comes pre-loaded with the program?

    1. i am also really confused about this :D

    2. It comes with a pre-loaded need to train and program it using its keyboard

  2. This comment has been removed by the author.

    1. I will love to make more inquiry on the HM 2007 ic. pls send me ur emai address via:

  3. Does it mean that i can buy HM2007 off any market? I dont need to buy the ic as part of the kit?
    Can i buy any Hm2007 IC and connect as per the schematics and i will be able to train the IC?

  4. can u please tell us what are components used with the resistor values and all the diodes etc in detail

  5. Hello author. ! we r working on speech recognition ..but the most problematic thing we facing is the footprint of our IC Hm2007( Plcc version with 52 pins) .we r not getting anything related to the ic in any of the softwares like Eagle and Proteus for schematic.we have tried introducing new libraries but no success .so kindly help us out of this...reply asap mail id is : Thanks !!

  6. i have made the speech recognition system but the ketpad isnt working what should be done plz help me. is there any special keypad for this system?

  7. hi Unais. I am from pakistan and i m intersted in buying this complete ic kit can u please guide me how to avail this..

  8. hi! how to make HM2007 speaker dependent?


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