void OnDataAvailable(object sender, WaveInEventArgs e)
        {
            byte[] buffer        = e.Buffer;
            int    bytesGrabados = e.BytesRecorded;

            for (int i = 0; i < bytesGrabados; i++)
            {
                lblMuestra.Text = buffer[i].ToString();
            }

            writer.Write(buffer, 0, bytesGrabados);
        }