recorded audio file cannot see in the android extrnal storage

i am recording audio clips in android by using following code. but my question is that i cannot see the recorded file in the emulator's storage. please someone help me to solve this problem or is there any solution to record a audio by using AudioRecode ??

 public class RecorderActivity extends Activity {
 private static final int RECORDER_SAMPLERATE = 8000;
 private static final int RECORDER_CHANNELS = AudioFormat.CHANNEL_IN_MONO;
 private static final int RECORDER_AUDIO_ENCODING = 
 AudioFormat.ENCODING_PCM_16BIT;
 private AudioRecord recorder = null;
 private Thread recordingThread = null;
 private boolean isRecording = false;
private String filePath = null;
@Override
public void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.main);
setButtonHandlers();
 enableButtons(false);

int bufferSize = AudioRecord.getMinBufferSize(RECORDER_SAMPLERATE,
    RECORDER_CHANNELS, RECORDER_AUDIO_ENCODING);

System.out.println("BUFFER SIZE VALUE IS " + bufferSize);

}
private void setButtonHandlers() {
((Button) findViewById(R.id.btnStart)).setOnClickListener(btnClick);
((Button) findViewById(R.id.btnStop)).setOnClickListener(btnClick);
}

private void enableButton(int id, boolean isEnable) {
((Button) findViewById(id)).setEnabled(isEnable);
}

private void enableButtons(boolean isRecording) {
enableButton(R.id.btnStart, !isRecording);
enableButton(R.id.btnStop, isRecording);
}

int BufferElements2Rec = 1024; // want to play 2048 (2K) since 2 bytes we      use only 1024
int BytesPerElement = 2; // 2 bytes in 16bit format

private void startRecording() {

recorder = new AudioRecord(MediaRecorder.AudioSource.MIC,
    RECORDER_SAMPLERATE, RECORDER_CHANNELS,
    RECORDER_AUDIO_ENCODING, BufferElements2Rec*BytesPerElement);
recorder.startRecording();

isRecording = true;

recordingThread = new Thread(new Runnable() {

public void run() {

    writeAudioDataToFile();

}
}, "AudioRecorder Thread");
recordingThread.start();
}

private byte[] short2byte(short[] sData)
{
int shortArrsize= sData.length;
byte[] bytes = new byte[shortArrsize*2];

for (int i=0; i < shortArrsize; i++)
{
bytes[i*2] = (byte) (sData[i] & 0x00FF);
bytes[(i*2)+1] = (byte) (sData[i] >> 8);
sData[i] = 0;
}
return bytes;

}


private void writeAudioDataToFile() {
// Write the output audio in byte

filePath = "/sdcard/voice8K16bitmono.pcm";
short sData[] = new short[BufferElements2Rec];

FileOutputStream os = null;
try {
os = new FileOutputStream(filePath);
} catch (FileNotFoundException e) {
e.printStackTrace();
}

while (isRecording) {
// gets the voice output from microphone to byte format

recorder.read(sData, 0, BufferElements2Rec);

try {
    // // writes the data to file from buffer
    // // stores the voice buffer
    byte bData[] = short2byte(sData);
    os.write(bData, 0, BufferElements2Rec*BytesPerElement);
} catch (IOException e) {
    e.printStackTrace();
}
}

try {
os.close();
} catch (IOException e) {
e.printStackTrace();
}
}

private void stopRecording() {
// stops the recording activity

if (null != recorder) {
isRecording = false;

recorder.stop();
recorder.release();

recorder = null;
recordingThread = null;
}
}

private View.OnClickListener btnClick = new View.OnClickListener() {
public void onClick(View v) {
switch (v.getId()) {
case R.id.btnStart: {
    enableButtons(true);
    startRecording();
    break;
}
case R.id.btnStop: {
    enableButtons(false);
    stopRecording();
    break;
}
}
}
};

@Override
public boolean onKeyDown(int keyCode, KeyEvent event) {

if (keyCode == KeyEvent.KEYCODE_BACK) {

finish();
}
return super.onKeyDown(keyCode, event);
}


}