Noise reduction in sound forge 5.0

I have sound forge 5.0 ony computer.  Ian using noise reduction to eliminate noise in digital audio that was recorded using I-phone 4s.
The audio is poor quality.  And so I need to clean it up for transcription.

i can hear what's on the audio, but the red scribed insists they can't.

I've used every trick I know to eliminate this persistent noise in the low volume Audio.  I've used multiband dynamics but the threshold features are very complicated.  So I used 50:1 ratio at -50db threshold and 0 gain.  This works well when used with para metrics to eliminate 60 hz? 120hz, 180hz audio hum.  Yes the contents of the audio is so low that the 120hz hum overpowers the audio.  But once the audio low frequency him is gone, I can't get rid of the noise at mid frequencies. I've tried soft knee limiter compressor to raise the low volumes and limit the higher volumes, but then that low noise and warble come into play and makes the audio even more difficult to hear.  I've used noise reduction 0 mode, 0db nr, followed by 0 mode 5db nr, then 0 mode 12db nr, then 0 mode 26db nr with noise floor raised to 6 db.  Works well, but but allows warping and reduced the audio to berry low to the point if inaudible.  Tried to volume after noise reduction with and without compression, but always noise jumps right back up with increasing volume.  How do I clean up this mid frequency persistent grinding and airplane hovering noise and yet increase the the low volume speech in the audio?