Estoy creando una aplicación para Android que muestra la Frecuencia de una nota sostenida con el algoritmo FFT. Estoy usando métodos de Jtransform. Mi problema actualmente es que no puedo mostrar la frecuencia en la pantalla. El siguiente código es el cálculo de frecuencia fft y AsynchTask, que debe mostrar la frecuencia en un cuadro de texto

import edu.emory.mathcs.jtransforms.fft.DoubleFFT_1D;

public class Tuning extends Activity implements OnClickListener{

    int audioSource = MediaRecorder.AudioSource.MIC;    // Audio source is the device mic
    int channelConfig = AudioFormat.CHANNEL_IN_MONO;    // Recording in mono
    int audioEncoding = AudioFormat.ENCODING_PCM_16BIT; // Records in 16bit


    private DoubleFFT_1D fft;                           // The fft double array
    int blockSize = 1024;                               // deal with this many samples at a time
    int sampleRate = 44100;                             // Sample rate in Hz
    public double frequency = 0.0;                      // the frequency given

    RecordAudio recordTask;                             // Creates a Record Audio command
    TextView tv;                                        // Creates a text view for the frequency


    // On Start Up
    @Override
    public void onCreate(Bundle savedInstanceState){
        super.onCreate(savedInstanceState);
        setContentView(R.layout.tuning);

        tv = (TextView) findViewById(R.id.lbl1);

    }


    // The Record and analysis class
    private class RecordAudio extends AsyncTask<Void, Double, Void>{
    @Override
    protected Void doInBackground(Void... params){      

        /*Calculates the fft and frequency of the input*/
        try{
            int bufferSize = AudioRecord.getMinBufferSize(sampleRate, channelConfig, audioEncoding);                // Gets the minimum buffer needed
            AudioRecord audioRecord = new AudioRecord(audioSource, sampleRate, channelConfig, audioEncoding, bufferSize);   // The RAW PCM sample recording

            short[] buffer = new short[blockSize];          // Save the raw PCM samples as short bytes
            double[] audioDataDoubles = new double[(blockSize*2)]; // Same values as above, as doubles

            double[] re = new double[blockSize];
            double[] im = new double[blockSize];
            double[] magnitude = new double[blockSize];

            audioRecord.startRecording();                   // Start working

            fft = new DoubleFFT_1D(blockSize);

            while(started){
                /* Reads the data from the microphone. it takes in data 
                 * to the size of the window "blockSize". The data is then
                 * given in to audioRecord. The int returned is the number
                 * of bytes that were read*/

                int bufferReadResult = audioRecord.read(buffer, 0, blockSize);

                // Read in the data from the mic to the array
                for(int i = 0; i < blockSize && i < bufferReadResult; i++) {

                    /* dividing the short by 32768.0 gives us the 
                     * result in a range -1.0 to 1.0.
                     * Data for the compextForward is given back 
                     * as two numbers in sequence. Therefore audioDataDoubles
                     * needs to be twice as large*/

                    audioDataDoubles[2*i] = (double) buffer[i]/32768.0; // signed 16 bit
                    audioDataDoubles[(2*i)+1] = 0.0;
                }

                //audiodataDoubles now holds data to work with
                fft.complexForward(audioDataDoubles);

                // Calculate the Real and imaginary and Magnitude.
                for(int i = 0; i < blockSize; i++){
                    // real is stored in first part of array
                    re[i] = audioDataDoubles[i*2];
                    // imaginary is stored in the sequential part
                    im[i] = audioDataDoubles[(i*2)+1];
                    // magnitude is calculated by the square root of (imaginary^2 + real^2)
                    magnitude[i] = Math.sqrt((re[i] * re[i]) + (im[i]*im[i]));
                }

                double peak = -1.0;
                // Get the largest magnitude peak
                for(int i = 0; i < blockSize; i++){
                    if(peak < magnitude[i])
                        peak = magnitude[i];
                }
                // calculated the frequency
                frequency = (sampleRate * peak)/blockSize;

                /* calls onProgressUpdate
                 * publishes the frequency
                 */
                publishProgress(frequency);
            }

        } catch(Throwable t){
            Log.e("AudioRecord", "Recording Failed");
        }
        return null;
    }


    // This should display the Frequency
    protected void onProgressUpdate(Double value){

        //print the frequency 
        setContentView(R.layout.tuning);
        String info = Double.toString(value);

        //TextView doubleView = (TextView) findViewById(R.id.DoubleView);
        tv.setText(info);
    }

    // For the click of the button
   public void onClick(View v){
       if(started){
           started = false;
           startStopButton.setText("Start");
           recordTask.cancel(true);
       } else {
           started = true;
           startStopButton.setText("Stop");
           recordTask = new RecordAudio();
           recordTask.execute();
       }
   }

He comprobado otras preguntas similares y no puedo encontrar la falla en mi código.

EDITAR: adicionalonClick() codificar. Sé que la frecuencia se está calculando, y según Eclipse, en ningún momento es elonProgressUpdate() siendo llamado.