I think there are several ways to improve listening skills. I used them when I studied for my TOFEL test and got a decent score. These are listed from the easiest way to the hardest.
Note: TL;DR. Method II and III will be the most helpful and effective ones to improve your listening before your test is due.
Note is added after I finished answering lol.
I. Watching/listening to Chinese programs/shows FROM CCTV
As many answers have mentioned, listening to Chinese programs will definitely help with your listening by letting you get used to the Chinese way of speaking.
I recommend you find programs from CCTV with bilingual subtitles because those are guaranteed to have more correct/clear content than programs from other channels or online. They should also be more similar to your test material than other programs(since they use standard Mandarin.)
If you pick an interesting program, you won't get bored.
While preparing for a listening test, I find the most effective way is to do dictation, meaning that you listen to an audio and type/write down what you hear sentence by sentence, then compare what you have to what is actually being said.
Since you are actively participating in hearing(you have to focus or you won't be able to write down the sentence), when you see the correct transcript of a sentence, you will immediately know what you got wrong, and why you got that wrong.
You mentioned that you have some hearing loss and the audio sound is small, so I think this method will help you the most. It focuses more on pronunciation not comprehension. This takes a very long time, especially for the first few tries, but it pays well. (It took me an hour to do my first two-minute audio:p)
III. Converse with real people
This is listed as the third just because I assume it's hard to find a native speaker to talk with. I know you are only looking for improving your listening not speaking, but the merit of talking to a real person is you can ask questions any time. This you cannot get from any other methods.
Conversation basically is the way to learn a language. Go for it.
IV. Watch Shows
This one is put as the last because I think most Chinese shows that are meant for entertainment either don't have good bilingual translations or don't have translations at all. Also most of them use too much slang and is edited so that sometimes it's hard to hear even for a native speaker.
Also, shows will sure grab your attention and you won't be focusing on the language. (But you can do this after your test if you still want to improve. Shows are fun!)