int AUDIO_ENCODING = AudioFormat.ENCODING_PCM_16BIT;
int FREQUENCY = 22050; //Herz
double REC_DURATION = 5.0; // in seconds
int bufferSize = -1;    
AudioRecord audioRecord = null;
short [] buffer = null; // data sink for recording the audio stream from mic
    

void initAudio() {
        
    int minBufferSize = AudioTrack.getMinBufferSize(FREQUENCY, AudioFormat.CHANNEL_OUT_MONO, AUDIO_ENCODING);    
        
    bufferSize = (int)(REC_DURATION * 10 * minBufferSize);
        
    buffer = new short[bufferSize];
        
    // Create new AudioRecord object to record the audio. 
    audioRecord = new AudioRecord(
        MediaRecorder.AudioSource.MIC, 
        FREQUENCY, AudioFormat.CHANNEL_IN_MONO, 
        AUDIO_ENCODING, bufferSize);    
}


public void record() {
        
    try {
        audioRecord.startRecording();
        audioRecord.read(buffer, 0, bufferSize);
        audioRecord.stop();
        } catch (Throwable t) {
           Log.e(ACTIVITY_NAME,"record(): Recording Failed");
    }   
}
    

private void saveToSDCard(){

    java.text.SimpleDateFormat sdf = new java.text.SimpleDateFormat("yyyy.MM.dd HH.mm.ss");
    String fileName = sdf.format(new java.util.Date());
        
    try {
            
        String rootS = Environment.getExternalStorageDirectory().toString();
        File root = Environment.getExternalStorageDirectory();
            
        if (root.canWrite()){
                
               File f = new File(rootS + "/AudioClassifier", fileName + ".txt");
               FileWriter fw = new FileWriter(f);
               BufferedWriter out = new BufferedWriter(fw);
                
                for(int i = 0; i < bufferSize / 2; i++){
                    out.write("" + buffer[i] + " ");
                 }
                 out.close();
                 fw.close();
        }
    } catch (IOException e) {
            e.printStackTrace();
    }
}