Mark a stack of practice papers and a pattern shows up quickly: the student heard the answer and still lost the mark. A misspelled word is wrong. A number written with the digits swapped is wrong. A plural written singular is wrong. None of that is a listening problem, and all of it is fixable in a fortnight.
Spelling. The test spells hard words out loud for you — names, streets, email addresses — and the letters that ruin answers are the ones that sound alike: M and N, S and F, B and P, D and T, G and J, and the vowel pairs A/E/I. Learn to hear them under pressure by dictating them to yourself, not by reading them.
Numbers. Two traps do most of the damage. The first is the pair thirteen and thirty, fourteen and forty, and so on: in natural speech the difference is where the stress lands, not how long the word is. The second is a correction. Speakers in this test change their minds on purpose — "it's forty-two pounds, sorry, forty-five" — and the mark goes to whoever wrote the second number.
Grammar of the gap. Read the sentence around the gap and check the answer fits it. If the sentence says "students must bring their own …", the answer is almost certainly plural. If it says "the tour starts at …", it wants a time, and "at 9" is safer than "9 o'clock in the morning" when the limit is two words.
None of this is about hearing better. It is about writing what you heard in the form the answer sheet will accept.