The following are the instructions to install Julius and Python binding in Ubuntu 14.04.2:

To install pyjulius, the Python extension for Julius, you need to install the setup tools in Python.

This command will start a Julius server. This server listens to clients. If we want to use Julius APIs from Python, we need to connect to a server using a client code as given in the following sections. The Python code is a client that connects to the Julius server and prints the recognized text.

The following code is a Python client of the Julius speech recognition server that we started using the previous command. After connecting to this server, it will trigger speech-to-text conversion and fetch the converted text and print on terminal:

#!/usr/bin/env python
import sys

#Importing pujulius module
import pyjulius

#It an implementation of FIFO(First In First Out) queue suitable for multi threaded programming.
import Queue

# Initialize Julius Client object with localhost ip and default port of 10500 and trying to connect server.
client = pyjulius.Client('localhost', 10500)
try:
    client.connect()
#When the client runs before executing the server it will cause a connection error.
except pyjulius.ConnectionError:
    print 'Start julius as module first!'
    sys.exit(1)


# Start listening to the server
client.start()
try:
    while 1:
        try:
            #Fetching recognition result from server
        	   result = client.results.get(False)
        except Queue.Empty:
            continue
        print result
except KeyboardInterrupt:
    print 'Exiting...'
    client.stop()  # send the stop signal
    client.join()  # wait for the thread to die
    client.disconnect()  # disconnect from julius

After connecting to Julius server, the Python client will listen to server and print the output from the server.

The acoustic models we used in the preceding programs are already trained, but they may not give accurate results for our speech. To improve the accuracy in the previous speech recognition engines, we need to train new language and acoustic models and create a dictionary or we can adapt the existing language model using our voice. The method to improve accuracy is beyond the scope of this chapter, so some links to train or adapt both Pocket Sphinx and Julius are given.

The following link is used to adapt the existing acoustic model to our voice for Pocket Sphinx:

http://cmusphinx.sourceforge.net/wiki/tutorialadapt

Julius accuracy can be improved by writing recognition grammar. The following link gives an idea about how to write recognition grammar in Julius:

http://julius.sourceforge.jp/en_index.php?q=en_grammar.html

In the next section, we will see how to connect Python and speech synthesis libraries. We will work with the eSpeak and Festival libraries here. These are two popular, free, and effective speech synthesizers available in all the OS platforms. There are precompiled binaries available in Ubuntu in the form of packages.

eSpeak and Festival are speech synthesizers available in the Ubuntu/Linux platform. These applications can be installed from the software package repository of Ubuntu. The following are the instructions and commands to install these packages in Ubuntu.

Here is the code to work with Python and eSpeak. As you will see, it's very easy to work with Python binding for eSpeak. We need to write only two lines of code to synthesize speech using Python:

from espeak import espeak
espeak.synth("Hello World")

This code will import the eSpeak-Python wrapper module and call the synth function in the wrapper module. The synth function will synthesize the text given as argument.

The following code shows how to synthesize speech using Python and Festival:

import festival
festival.say("Hello World")

The preceding code will import the Festival-Python wrapper module and call the say function in the Festival module. It will synthesize the text as speech.