AJUDA!!Trabalhar com sensor de proximidade

Código:
import android.content.Context;

import android.content.Intent;

import android.hardware.Sensor;

import android.hardware.SensorEvent;

import android.hardware.SensorEventListener;

import android.hardware.SensorManager;

import android.media.MediaRecorder;

import android.os.Bundle;

import android.os.Environment;

import android.support.v7.app.ActionBarActivity;

import android.view.Menu;

import android.view.View;

import android.widget.Toast;

import java.io.IOException;









public class Classe1 extends ActionBarActivity implements SensorEventListener {



    private SensorManager mSensorManager;

    private Sensor mProximity;

    private MediaRecorder gravador;





    @Override

    protected void onCreate(Bundle savedInstanceState) {

        super.onCreate(savedInstanceState);

        setContentView(R.layout.activity_classe1);





        gravador = new MediaRecorder();

        mSensorManager = (SensorManager) getSystemService(Context.SENSOR_SERVICE);

        mProximity = mSensorManager.getDefaultSensor(Sensor.TYPE_PROXIMITY);



    }



    @Override

    public void onAccuracyChanged(Sensor sensor, int accuracy) {



    }



    @Override

    public final void onSensorChanged(SensorEvent event) {



        if(event.values[0] > 3  ){





        }

        else{

            startRecording();

        }





        // stopRecording();

        //Intent intent=new Intent(this, Reproduzir.class);

        //startActivity(intent);





    }









    @Override

    protected void onPause() {



        super.onPause();

        mSensorManager.unregisterListener(this);





        }



    @Override

    protected void onResume() {





        super.onResume();

        mSensorManager.registerListener(this, mProximity, SensorManager.SENSOR_DELAY_NORMAL);











        }







    @Override

    protected void onStop() {



        super.onStop();

        mSensorManager.registerListener(this, mProximity, SensorManager.SENSOR_DELAY_NORMAL);

        mSensorManager.unregisterListener(this);



    }



    private void startRecording() {



        gravador = new MediaRecorder();

        gravador.setAudioSource(MediaRecorder.AudioSource.MIC);

        gravador.setOutputFormat(MediaRecorder.OutputFormat.THREE_GPP);

        gravador.setAudioEncoder(MediaRecorder.AudioEncoder.AMR_NB);

        String filename = Environment.getExternalStorageDirectory().getAbsolutePath() + "/test2.3gp";

        gravador.setOutputFile(filename);

        try {

        gravador.prepare();

        gravador.start();

        } catch (IllegalStateException e) {

        e.printStackTrace();

    } catch (IOException e) {

        e.printStackTrace();

    }

    Toast.makeText(getBaseContext(), "A gravar....", Toast.LENGTH_SHORT).show();

}



         private void stopRecording() {

         gravador.stop();

         gravador.release();

         Toast.makeText(getBaseContext(), "Gravação concluída!!", Toast.LENGTH_SHORT).show();





        }







    public void close(View view) {

        Intent botaofechar= new Intent(this, MainActivity.class);

        startActivity(botaofechar);



    }







    @Override

    public boolean onCreateOptionsMenu(Menu menu) {

        getSupportActionBar().setDisplayShowHomeEnabled(true);

        getSupportActionBar().setLogo(R.mipmap.micro);

        getSupportActionBar().setDisplayUseLogoEnabled(true);

        return true;

    }



}