Sorry if I'm in the wrong forum, this was my best guess. I understand the term "title sequence" is used for a musical introduction in television. But what would you call it if it's audio only? I've done an intro for a series of language courses, we called it a jingle but that doesn't really seem like the right term. It's a 30 second musical intro with phrases in different languages that's in the beginning of all of their courses (on CD or mp3).
Intro, Main Title, Opening Theme - any number of terms are used. Doesn't much matter as long as everyone knows what it is referring to. "Jingle" would be a radio term for an advertising song usually containing vocals.