XFTroop
What this NATO report of 2010 is saying is that both the pilots, and anyone in the rear, of the C130 variants in the RAF suffer excessive noise dose - in varying degrees. The point is it seems to contradict the information you were given some years ago.
To the figures shown in the graph you must add the noise from intercom, which in C130 is very high (according to the same report), exceeded only by the likes of HS125. The noise must be measured at the operator's ear; not simply in the cockpit/cabin space (which would not include intercom noise).
It is not unusual for crew in different seats to be exposed to different levels of noise, at different frequencies. Furthermore, what this graph illustrates is that the dominant frequencies in a C130 are quite low compared to, for example, helicopters where they tend to be related to transmission components nearer 1kHz.
This means the solution must target specific frequencies to be effective. It must also let the subject hear certain audio cues, which differ from aircraft to aircraft. For this reason, a broadband ANR system, similar to those used by troops in the back of APVs, is more often than not useless (and dangerous) in an aircraft. Most commercial ANR systems fall into this category. This is why MoD developed their own. (Yet from various PMs I've received it seems some aircrew have been given simplistic broadband systems).
There are two basic ways around this. First, you design a raft of analog systems, each designed for a particular application; which brings major logistic problems and expense. Or, you have a digital, programmable system in which the EPROM in the headset/helmet is "blown" if you change environments. (Meaning, in the main, changing between aircraft types, but retaining your own, properly fitted, helmet; which is a major factor in all this. How many have a laser mapped/cut helmet shell? It adds a few pounds to the cost, but makes the system infinitely more effective. This has been on offer at MoD's supplier since about 1996, but seldom if ever used. The biggest expense is actually sending the aircrew to the factory for a half day to be fitted).
The former (analog) was used in what was effectively the Technology Demonstrator Programme in MoD, for one aircraft fleet. This was rendered obsolescent in 2000 following successful trials of the latter. Thereafter, it was a "simple" case of conducting noise surveys in each aircraft and modifying the basic software accordingly.
It was at this point (2000) the job could no longer be progressed by the lead project team, as they only had control over their own aircraft. It needed a higher level, pan-MoD requirement to be endorsed. As I said above, this had been anticipated and the Board Submission prepared in 1998, so that the wider programme could follow-on seamlessly. But work ceased, or at least slowed down to a crawl, because the practical problem in MoD is that such programmes need a "champion", and that usually means a technical expert/Staff Officer who can both articulate the requirement and staff it through the disbelievers. And has time to do it. The MoD system militates against this. Hence, the scattergun, uncoordinated approach we see.
The main problem faced by project teams in MoD is the failure to integrate the R&D work (in this case, Applied Research Packages) and the application of the technology (Development, Production, In-Service). The APRs would deliver the theory, but there was no practical means of PTs knowing what this had produced, so a lot of wheel reinventing went on.
AbbeyWood has (had?) an outfit called FBG who were meant to coordinate things like this. A database was planned in the late 90s - you type in a key word like "noise" and up popped a list of ARPs, endorsed requirements, contracts, who uses what, points of contact etc. That this didn't materialise is obvious, witness (again) the Nimrod example from 2007 when they sought to repeat (unwittingly at first, then deliberately) R&D from the 70s and 80s; when all it need was to walk next door and ask for a floppy disk of the work finished years ago by their neighbouring IPT.
Hope this helps. (You did ask!).