Page 167 - Robots Androids and Animatrons : 12 Incredible Projects You Can Build

Isolated
These speech-recognition systems can just handle words that are
spoken separately. This is the most common speech-recognition
system available today. The user must pause between each word or
command spoken. Our speech-recognition circuit will use isolated
words.
Connected
This is a halfway point between isolated word and continuous
speech recognition. It allows users to speak multiple words. The
HM2007 can be set up to identify words or phrases 1.92 s in length.
This reduces the word recognition dictionary number to 20.
Continuous

This is the natural conversational speech we use in everyday life.
It is extremely difficult for a recognizer to shift through the text
since the words tend to merge together. For instance, “Hi, how are
you doing?” sounds like “Hi, howyadoin.” Continuous speech-
recognition systems are on the market and are under continual
development.

Building the speech-recognition circuit
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The demonstration circuit operates in the HM2007’s manual mode.
This mode uses a simple keypad and microphone to program the
HM2007 chip.
Keyboard
The keyboard is a telephone keypad made up of 12 normally open
switches.
1 2 3
4 5 6
7 8 9
Clear 0 Train
When the circuit is turned on, the HM2007 checks the onboard
static RAM. If the RAM checks out, the board displays “00” on the
seven-segment display chips, lights the red light-emitting diode
(LED) (Ready), and waits for a command.
To train
Press “1” (display will show “01”) and the LED will turn off. Then
press “T” (Training), and the LED will turn back on.
Hold the microphone close to your mouth and say the training word.
For instance, let’s use the word “computer” as the training word. Say
Team LRN
Chapter seven