Walter's pretty much "NAILED IT" .... I believe
.... and so has Garry too .... to a certain extent also
I think it was Abraham LINCOLN that once famously commented ....
"one can please some of the people some of the time, but, not all of the people all of the time". And from an HJG or other FS group perspective the very same can be applied also .... in that no matter how authentic something is made to look, sound, and function .... it simply "CANNOT" please everyone
I realize .... "as well as respect also" .... that some FS folk simply don't care for various features (like authentic FD audio), but, the thing is that those ("HERE") whom are responsible for engineering the panels HJG represent, along with the sound packs offered by HJG also, do care for such details .... and which is why these are, and will continue to be, implemented
ABOUT THE INVERTERS/AVIONICS SOUNDS on aircraft FD's .... and in particular the volume of these.
Different aircraft types exhibit "quite different sounds" in respect of these details. This audio can range from different tones of constant "WHINE" (the most common example), to a soft and constant "TICKING" sounds .... each of which is often, usually, recorded from "the actual real world beast" and then engineered into the panel/gauge sounds or sound packs which HJG represents.
I wouldn't say that such sounds (real world) are so loud as to impair the audibility of communication between people "on any FD" .... but .... will say that "depending on both the sensitivity and proximity of camera, and other recording devices, to various FD systems during filming/recording processes .... and how these recording devices are actually wired-in/set up on the FD" .... then the result of what's recorded can, sometimes, convey such an erroneous impression.
I recall a certain FD video I had .... shot on the FD of an ANSETT aircraft .... and which, unfortunately, due to precisely what I've stated above, captured more Inverter/Avionics sound (a constant WHINE" right throughout the entire 15 minute duration of this particular recording) than environmental, engine (not much engine noise can be heard on the FD's of most jetliner types anyway), mechanical, and crew inter-communication than anything else .... and which was "very disappointing" .... simply because this particular video, as good as it otherwise was, became "absolutely useless" in terms of it being of any reference value in regard to assessing the type, tone, and volume associated with such FD audio .... "for this particular ANSETT aircraft type at least".
The DC8 FD .... and from my own personal jump seat experience aboard these aircraft .... is quite noisey (certainly more-so than the B747, B767, and DC10) than most other FD's I'm reasonably familiar with. Over the sound of background avionics ....
"BUT OVER THE SOUND OF ENVIRONMENTAL BACKLGROUND NOISE IN PARTICULAR" (the real/raw volume of which is often filtered out/down in a lot of post recording editing/production otherwize one wouldn't be able hear much at all).... results in good, clear/precise, reasonably loud communication needing to happen (on any FD really), but which, generally
"IS NOT" any problem.
As a comparison (but digressing somewhat also) I'd have to rate both the GRUMMAN GOOSE and GRUMMAN WIDGEON as
"THE NOISIEST" FD's I've ever experienced (all engine/prop noise
) .... but .... one's got to expect that of such aircraft of course. In fact the volume of engine/prop sound on the GOOSE and WIDGEON was "LOUD" enough for some long serving crews (I knew) to eventually develop hearing impairments
.... but still .... a lot of audio-visual recording simply doesn't, really, capture this detail in true proportion.
Secondly .... AND COMING BACK TO PANELS ONCE AGAIN ....
For me .... at least .... the greater concern is when people start fiddling with, and even eliminating, various components .... sometimes going so far as recommend others consider doing the same also. Depending upon how some panels are engineered .... one can, sometimes, "get away with doing this" and without imposing any problems upon oneself, but on other panels, such fiddling may cause "some" (not all) panels/simulations to then become "UNSTABLE/CRASH". And from an FS group SUPPORT perspective .... all that ever does is make HJG's job "a lot more frustrating and difficult" as it then tries to analyze/troubleshoot what people report .... simply because, 6 times out of 10 times, people only ever tell HJG what they want it to know "rather than precisely what they've actually done" thats sparked their problem.
It's not easy .... somtimes
Mark C
AKL/NZ
;D .... the sound (Inverters/avionics) is both "intentional" and "VERY AUTHENTIC" too .... having been recorded (by Marco) directly from "a DC8 flightdeck" .... and .... the proportion of it's raw volume "is about right", and which I can most certainly attest to, having spent more than a flight or 2 in the jumpseat aboard both DC8-52 and -63 aircraft in the past. That sound is "very noticeable" on the DC8 flightdeck .... and in PAX cabin too, but, to a much lesser extent.
) .... but .... one's got to expect that of such aircraft of course. In fact the volume of engine/prop sound on the GOOSE and WIDGEON was "LOUD" enough for some long serving crews (I knew) to eventually develop hearing impairments 
.... but still .... a lot of audio-visual recording simply doesn't, really, capture this detail in true proportion.