Voice and Speech Recognition – Java Speech Recognition Libraries

Java, a versatile and widely used programming language, offers several libraries and tools for voice and speech recognition applications. In this article, we’ll explore the role of Java in voice and speech recognition and delve into key libraries with code examples.

1. Java in Voice and Speech Recognition

Java’s platform independence, strong community support, and rich ecosystem make it an attractive choice for voice and speech recognition applications:

a. Platform Independence: Java applications can run on various platforms, making them accessible to a wide audience.

b. Extensive Ecosystem: Java’s vast collection of libraries and frameworks simplifies the development of voice and speech recognition solutions.

2. Java Speech Recognition Libraries

Java provides libraries and APIs for speech recognition, enabling developers to integrate voice-based features into their applications. Let’s explore a few of them:

2.1 Sphinx4

Sphinx4 is an open-source speech recognition system that supports multiple languages. Here’s an example of using Sphinx4 for simple speech recognition:

import edu.cmu.sphinx.api.Configuration;
import edu.cmu.sphinx.api.LiveSpeechRecognizer;

public class Sphinx4Example {
    public static void main(String[] args) throws Exception {
        Configuration configuration = new Configuration();

        configuration.setAcousticModelPath("models/en-us");
        configuration.setDictionaryPath("models/en-us/cmudict-en-us.dict");
        configuration.setLanguageModelPath("models/en-us/en-us.lm.dmp");

        LiveSpeechRecognizer recognizer = new LiveSpeechRecognizer(configuration);

        recognizer.startRecognition(true);

        while (true) {
            System.out.println("Say something...");
            String speech = recognizer.getResult().getHypothesis();
            System.out.println("You said: " + speech);
        }
    }
}

In this code, Sphinx4 is used to perform live speech recognition in English. It captures and transcribes spoken words in real time, making it suitable for applications like voice assistants and voice-controlled systems.

2.2 CMU PocketSphinx

CMU PocketSphinx is a lightweight speech recognition engine designed for mobile and embedded devices. Here’s an example of using CMU PocketSphinx for keyword spotting:

import edu.cmu.sphinx.api.Configuration;
import edu.cmu.sphinx.api.LiveSpeechRecognizer;

public class PocketSphinxExample {
    public static void main(String[] args) throws Exception {
        Configuration configuration = new Configuration();

        configuration.setAcousticModelPath("models/en-us");
        configuration.setDictionaryPath("models/en-us/cmudict-en-us.dict");
        configuration.setGrammarPath("models/en-us");
        configuration.setGrammarName("hello");
        configuration.setGrammarType("jsgf");

        LiveSpeechRecognizer recognizer = new LiveSpeechRecognizer(configuration);

        recognizer.startRecognition(true);

        while (true) {
            System.out.println("Listening for 'hello'...");
            String hypothesis = recognizer.getResult().getHypothesis();
            if ("hello".equalsIgnoreCase(hypothesis)) {
                System.out.println("Keyword 'hello' detected!");
            }
        }
    }
}

In this code, CMU PocketSphinx is used for keyword spotting, recognizing the word “hello.” It’s ideal for creating voice-activated commands and specific keyword triggers.

2.3 MaryTTS

MaryTTS is a text-to-speech synthesis system. While not a speech recognition library, it complements speech recognition by enabling applications to convert text into spoken language. Here’s a simple example:

import marytts.modules.synthesis.Voice;
import marytts.modules.synthesis.VoiceList;
import marytts.client.MaryClient;
import marytts.util.data.audio.AudioPlayer;

public class MaryTTSExample {
    public static void main(String[] args) throws Exception {
        MaryClient maryClient = MaryClient.getMaryClient();

        // List available voices
        VoiceList voiceList = VoiceList.getVoiceList();
        System.out.println("Available voices:");
        voiceList.stream().map(Voice::getName).forEach(System.out::println);

        // Set the desired voice
        String selectedVoice = "cmu-slt-hsmm";
        maryClient.processAndPlayText("Hello, I am MaryTTS, your text-to-speech companion!", selectedVoice);
    }
}

Here, MaryTTS is used to list available voices and synthesize text into speech using the selected voice.

3. Conclusion

Java provides a robust platform for voice and speech recognition applications, and libraries like Sphinx4, CMU PocketSphinx, and MaryTTS offer versatile solutions for developers. Whether you’re building voice assistants, voice-controlled systems, or text-to-speech applications, Java’s versatility and these libraries empower you to create innovative voice-based experiences.