title_body: While producing an audiobook, how to mark the begining of an unnamed and unnumbered section or chapter?
upvoted_answer: It really depends on the type of content you are producing and how many sections there are (and what they are about). 
  
  I've heard lots of readers just give a longer pause between sections, and that worked well. 
  
  On the other hand, flashbacks are already a unique beast and we are already accustomed to hearing or seeing some kind of cue. The standard I'd use is that if  listeners might be confused about when a flashback scene takes place, perhaps an additional cue should be inserted. 
  
  But some flashbacks flow so naturally into the text that this is never a problem (especially if you're using 1st person or 3rd person limited with a strong narrative voice). On the other hand, more omniscient narratives might require more cues.