Using Lame in android to encode WAV to MP3, result is a noise file

Question

I'm using Lame to encode wav to mp3 in android.

http://lame.sourceforge.net/ - LAME, with this tut. http://developer.samsung.com/android/technical-docs/Porting-and-using-LAME-MP3-on-Android-with-JNI, everything works good. creating the libmp3lame.so and the wrapper part. The problem here is, when i take a wav file to encode to a mp3 file, i receive an output file with a buzzie noise. Not sure if there is any configuration left out. The Code is below :

// encoding params initializing
public static final int NUM_CHANNELS = 2;
public static final int SAMPLE_RATE = 16000;
public static final int BITRATE = 48;
public static final int MODE = 1;
public static final int QUALITY = 2;  
private File mRawFile;
private File mEncodedFile;   

// the following is for encoding
initEncoder(NUM_CHANNELS, SAMPLE_RATE, BITRATE, MODE, QUALITY);
File path = Environment
                    .getExternalStoragePublicDirectory(Environment.DIRECTORY_DOWNLOADS);
//  encoding
            mRawFile = new File(path, "Vox_021.wav");
            mEncodedFile = new File(path, "newmp3.mp3");
            int result = encodeFile(mRawFile.getAbsolutePath(),
                    mEncodedFile.getAbsolutePath());
            if (result == 0) {
               Log.i("test", "encoded");
            }
            // / encoding done

The wav file "vox_021.wav" sample rate is 16000, Bit depth is 16 and stereo. I really dont know why the encoded mp3 file outputs noise. been working on this more than 2 days, any help will be appreciated.