Trumpet growls?

How do I do a trumpet growl? I'd like to do the one as in Sing, Sing, Sing I found in iTunes by BBC Big Band Orchestra. Or is that a mute?

Trumpet growls?
the growl comes from playing the note with your throat.
Reply:It's a combination of using a plunger mute and playing a note while making a growling sound at the same time at the back of your throat. Sort of like gargling.