IoT-For-Beginners/translations/en/6-consumer/lessons/1-speech-recognition/virtual-device-speech-to-text.md

Speech to text - Virtual IoT device

In this part of the lesson, you will write code to convert speech captured from your microphone into text using the speech service.

Convert speech to text

On Windows, Linux, and macOS, the Python SDK for speech services can be used to listen to your microphone and convert detected speech into text. It listens continuously, monitoring audio levels and sending speech for conversion to text when the audio level drops, such as at the end of a spoken phrase.

Task - convert speech to text

1. Create a new Python app on your computer in a folder named smart-timer with a single file called app.py and a Python virtual environment.

2. Install the Pip package for the speech services. Ensure you are installing this from a terminal with the virtual environment activated.

   pip install azure-cognitiveservices-speech
   

   ⚠️ If you encounter the following error:

   ERROR: Could not find a version that satisfies the requirement azure-cognitiveservices-speech (from versions: none)
   ERROR: No matching distribution found for azure-cognitiveservices-speech
   

   You will need to update Pip. Use the following command to update it, then try installing the package again:

   pip install --upgrade pip
   

3. Add the following imports to the app.py file:

   import requests
   import time
   from azure.cognitiveservices.speech import SpeechConfig, SpeechRecognizer
   

   These imports include classes used for speech recognition.

4. Add the following code to declare some configuration:

   speech_api_key = '<key>'
   location = '<location>'
   language = '<language>'
   
   recognizer_config = SpeechConfig(subscription=speech_api_key,
                                    region=location,
                                    speech_recognition_language=language)
   

   Replace <key> with the API key for your speech service. Replace <location> with the region you selected when creating the speech service resource.

   Replace <language> with the locale name for the language you will be speaking, such as en-GB for English or zn-HK for Cantonese. You can find a list of supported languages and their locale names in the Language and voice support documentation on Microsoft docs.

   This configuration is used to create a SpeechConfig object that configures the speech services.

5. Add the following code to create a speech recognizer:

   recognizer = SpeechRecognizer(speech_config=recognizer_config)
   

6. The speech recognizer operates on a background thread, listening for audio and converting detected speech into text. You can retrieve the text using a callback function—a function you define and pass to the recognizer. Each time speech is detected, the callback is triggered. Add the following code to define a callback, pass it to the recognizer, and define a function to process the text by writing it to the console:

   def process_text(text):
       print(text)
   
   def recognized(args):
       process_text(args.result.text)
   
   recognizer.recognized.connect(recognized)
   

7. The recognizer only begins listening when explicitly started. Add the following code to start the recognition process. This runs in the background, so your application will also need an infinite loop that sleeps to keep the application running.

   recognizer.start_continuous_recognition()
   
   while True:
       time.sleep(1)
   

8. Run this app. Speak into your microphone, and the audio converted to text will be displayed in the console.

   (.venv) ➜  smart-timer python3 app.py
   Hello world.
   Welcome to IoT for beginners.
   

   Experiment with different types of sentences, including sentences where words sound the same but have different meanings. For example, if you are speaking in English, say "I want to buy two bananas and an apple too," and observe how it correctly uses "to," "two," and "too" based on the context of the sentence, not just the sound.

💁 You can find this code in the code-speech-to-text/virtual-iot-device folder.

😀 Your speech-to-text program was a success!

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