It may help in two respects:
1. Very soft sounds are increased in volume, which might make certain things better understandable
2. The noise filter will probably also improve things... But don't expect too much from it if the noise level is high compared to the audio level.
However, most of the processing will also greatly increase the noise level, so I'm not sure if it will be pleasant to listen to the result. So I would suggest that you do some tests before making the actual recording to make sure that you wil be able to understand it afterwards.
The following filters may be useful:
- NOISE GATE filter to reduce the noise/hiss level
- Pre limiter to get a bit of gain control
- Final limiter with "do not preserve loudness" turned on. Or you could try the singleband compressor. Both can be found in the "Limiting & Loudness" panel.
The multiband compressor might also be useful, but don't use too much of it or you'll just increase the noise level way too much.
Of course you can also just try a number of presets to see if any of them improves the sound. (The ones under "GENERIC PRESETS" are probably most useful for this). I think you'll need to set the noise gate a bit more agressive.
Just in case: If you're using a recorder that records in stereo, you might want to try out my other plugin Tape Restore Live which (among others) contains a filter that removes noise by comparing the two channels... See http://www.hansvanzutphen.com/tape_restore_live/