maybe you should sample the sound with a prog like cool edit…
get the loop that you require and import that…
that way you will have the loop you require…
i personally import the sound as a wav file coz the mp3 option has an annoying click sound when it saves…export from flash as an mp3…adjust compression settings as required
"Event synchronizes the sound to the occurrence of an event. An event sound plays when its starting keyframe is first displayed and plays in its entirety, independently of the Timeline, even if the movie stops. Event sounds are mixed when you play your published movie.
An example of an event sound is a sound that plays when a user clicks a button. If an event sound is playing and the sound is instantiated again (for example, by the user clicking the button again) the first instance of the sound continues to play and another instance begins to play simultaneously.
Start is the same as Event, except that if the sound is already playing, no new instance of the sound is played.
Stop silences the specified sound.
Stream synchronizes the sound for playing on a Web site. Flash forces animation to keep pace with stream sounds. If Flash can’t draw animation frames quickly enough, it skips frames. Unlike event sounds, stream sounds stop if the movie stops. Also, a stream sound can never play longer than the length of the frames it occupies. Stream sounds are mixed when you publish your movie.
An example of a stream sound is the voice of a character in an animation that plays in multiple frames.
Note: If you use an MP3 sound as a stream sound, you must recompress the sound for export. You can choose to export the sound as an MP3 file, with the same compression settings that it had on import. See Compressing sounds for export.
Enter a value for Loop to specify the number of times the sound should loop.
For continuous play, enter a number large enough to play the sound for an extended duration. For example, to loop a 15-second sound for 15 minutes, enter 60.
Note: Looping stream sounds is not recommended. If a stream sound is set to loop, frames are added to the movie and the file size is increased by the number of times the sound is looped. "