get a trouble in loading a mp3 file to audioclip by using resource.load() on the fly?

 look at my source code first:
                 //i use filestream to write using a byte array which is a mp3 file
                 FileStream fs = new FileStream("Assets/Resources/voice.mp3", FileMode.Create);
                 fs.Write(outputb, 0, outputb.Length);
                 fs.Flush();
                 fs.Close();
                 //and now i want load the file i just wrote
                 GameObject menu=GameObject.Find("menu");
                 AudioSource menuAudio=menu.GetComponent<AudioSource>();
                 
                 menuAudio.clip=(AudioClip)Resources.Load("voice");
                 menuAudio.loop=false;
                 menuAudio.Play ();

every time,the audiosource play the music stored before,not the current file! i guess it was because that we should wait audiosource to load the file. so i add a sleep function:

 Thread.Sleep(5000);

but...it also do not work....and now it comes to play the same sound even though i load a new file to a clip... plz help me,what mistakes do i make in assigning a audioclip?