Legality of using commercial audio clips in music

Been meaning to ask this for a while. I wrote a song a while back, and in the break I have a sequence that features the famous Dirty Harry speech. (“I know what you’re thinking … did he fire six shots, or only five?”) In all not more than 15 seconds for the whole clip. (It’s been chopped up and somewhat altered to try and remove the mechanical alarm in the background) What’s the legal standing on the use of this clip? Being as short as it is, does it fall under fair use, or does fair use not apply because it’s used in what could be deemed a commercial song? (FWIW, the song is not available commercially, at least not yet.) I listen to a lot of music that tends to feature clips from movies in them. (Psy/goa trance is filled with such songs.) Do they have to secure rights to use those clips?

If you sample audio from a recognizable source, you need permission. You need permission even its an unrecognizable copyrighted source…but if you can’t tell, how do you enforce?

The exceptions:

  1. The audio sample is used in a journalistic review.

  2. The original owner has released their audio track as “fair use” - in effect giving everyone permission.

  3. The audio sample is aged beyond copyright protection.

Alright, so I definitely need permission – this is probably one of the most recognizable (and misquoted) pieces of movie pop culture. Is there a licensing fee involved in its use? Is permission typically granted for such things?