[ci skip] Add microphone example to README

Author: germanattanasio

README.md

@@ -418,6 +418,52 @@ RecognizeOptions options = new RecognizeOptions.Builder()
   // wait 20 seconds for the asynchronous response
   Thread.sleep(20000);
 ```
+#### Microphone example
+Use your microphone to recognize audio for 30 seconds.
+
+```java
+SpeechToText service = new SpeechToText();
+service.setUsernameAndPassword("<username>", "<password>");
+
+// Signed PCM AudioFormat with 16kHz, 16 bit sample size, mono
+int sampleRate = 16000;
+AudioFormat format = new AudioFormat(sampleRate, 16, 1, true, false);
+DataLine.Info info = new DataLine.Info(TargetDataLine.class, format);
+
+if (!AudioSystem.isLineSupported(info)) {
+  System.out.println("Line not supported");
+  System.exit(0);
+}
+
+TargetDataLine line = (TargetDataLine) AudioSystem.getLine(info);
+line.open(format);
+line.start();
+
+AudioInputStream audio = new AudioInputStream(line);
+
+RecognizeOptions options = new RecognizeOptions.Builder()
+  .continuous(true)
+  .interimResults(true)
+//.inactivityTimeout(5) // use this to stop listening when the speaker pauses, i.e. for 5s
+  .contentType(HttpMediaType.AUDIO_RAW + "; rate=" + sampleRate)
+  .build();
+
+service.recognizeUsingWebSocket(audio, options, new BaseRecognizeCallback() {
+  @Override
+  public void onTranscription(SpeechResults speechResults) {
+    System.out.println(speechResults);
+  }
+});
+
+System.out.println("Listening to your voice for the next 30s...");
+Thread.sleep(30 * 1000);
+
+// closing the WebSockets underlying InputStream will close the WebSocket itself.
+line.stop();
+line.close();
+
+System.out.println("Fin.");
+```
 
 ### Text to Speech
 Use the [Text to Speech][text_to_speech] service to get the available voices to synthesize.