comprehensible doesn't fit because it just means that you can grasp the concept or can understand. for example: you have a comprehensible reason for not showing up to work today. comprehensive would fit much better because you want to improve your ability to grasp or understand what you are listening to. for example: I need to improve my comprehensive listening skills because I can barely understand. hopefully that makes sense

Yes it fits it's an adjective describing what kind of listening she wants. A fuller kind of listening instead of casual or fragmentary listening. If you don't understand the use of a word find its opposite to see if it fits. Comprehensible = fully understandable incomprehensible = completely not understandable. Your examples * are right.

Thank you for your explanation Nanren888, it's misleading that these two have nothing to do with each other, but making up an expression that doesn't exist... is so irresponsible... :((

"comprehensible listening" -= nope. Not sensible, sorry. I suspect what they want is ... to improve one's listening comprehension. Comprehension is listening and understanding. Comprehensive means complete, total, not lacking anything. So it sort of has meaning, but a rather unnatural use. . To be more technical, you'd probably say aural comprehension. But that's not really a commonly used expression either.