Convert a Stream Object to File Stream In Silverlight

i am getting an audio file from server in silver light application. I am getting stream in a Stream object. I need to convert this is into "filestream". Is there is any solution to do this. Please help me out.

Here is the code.

string UrlString = SongURL
HttpWebRequest request = (HttpWebRequest)HttpWebRequest.Create(new Uri(UrlString));
request.BeginGetResponse(new AsyncCallback(ReadCallback), request);

 private void ReadCallback(IAsyncResult asynchronousResult)
        {
            this.Dispatcher.BeginInvoke(delegate()
            {
                HttpWebRequest request =
                              (HttpWebRequest)asynchronousResult.AsyncState;
                HttpWebResponse response =
                  (HttpWebResponse)request.EndGetResponse(asynchronousResult);
                //using (StreamReader streamReader1 =
                //  new StreamReader(response.GetResponseStream()))
                //{
                //    string resultString = streamReader1.ReadToEnd();
                //   // resultBlock.Text = "Using HttpWebRequest: " + resultString;
                //}
                Stream streamReader1 = response.GetResponseStream();
 }