In my research into listening and sound design I am becoming increasingly aware of the effects of presbycusis (age related hearing loss), which has its own ISO standard (7029). My question is do you take presbycusis into consideration when you are working for both yourself and the audience? Do you alter the design if the expected audience is older, or do you design for a generic listener?
I can't say that I have, but I've never had the brief to create something specifically for that age bracket.
It strikes me that perhaps the best way to tackle this is not in the mix of any material but how it's played back. The trouble is that the public are often uneducated and unwilling to callibrate the equipment they use.
I remember seeing a good TED talk a while back by the designer of the Humanscale Freedom chair; he spoke about this design related issue of nobody adjusting chairs before they sit in them, which is especially true in hot-desking environments which seem to be common at the moment. So the challenge was to create a chair which automatically adjusted to the person sitting in it. Similarly, how many times do you see people watching television with the colour so saturated everybody looks like they've had a spray tan accident?
With the issue of sound it becomes increasingly complex because more than one person can be listening to the same system, and they might all have different listening needs. I think the solution could be about creating systems with a bit of intelligence, ones that make use of the mass of information we gather. I don't see why the television of an elderly couple shouldn't communicate with the records of their local doctor and adjust the frequency response of their tv automatically, to the value which best serves them both. It's amazing how long we've had this sort of capability, discussed it and never made use of it. It's like the internet has been hijacked by Marketeers and it's true purpose has been forgotten...
Yes and no. I was originally trained as a mixture between apprentice and student into a music producer, and as such I was accustomed to mixing in several different systems, with a small and extremely low-middy speaker (probably around 100Hz to 5KHz, was 15 years ago) as an absolute reference. It could never really sound good in this ridiculous little cone built into the console, but if you got everything in it and with a good balance to that, and it sounded good in the "consumer-system" in the live room, then you knew it would pretty much sound if not great (after all, some people use their %&#%#¤ cellphones to listen to...without headphones...), then at least good, in pretty much all systems and for all listeners except those with the absolutely most messed up hearing. And they will not hear very much anyway.
As such, I'm not really mixing for any specific age, system, or ability to hear, I'm normally mixing everything so everyone would enjoy it, including both people with absolutely perfect hearing, and those with really bad ditto. I don't happily use the word "generic" as it for me is a pretty negative word (mind you, English is not my native language so chances is I make too much a deal of that word), but yes, I try to keep it general. In my firm belief and experience it's not really a problem making exciting sounds that works well for everyone, as long as one are aware of the limitations and mind them carefully. It's not always easy, but I do firmly believe there always is a way, even if it might be pretty hard to find sometimes.
Now, I still follow the same rules as I did as a musician, though movies is a lot different to mix philosophically. And they are in surround. Here, we strive much more towards a more natural impression (not to be confused with actually realistic), and use a lot more linear microphones in film than in music. As such, I've gotten used to low-passing most things much more heavily with slightly resonant filters (for example, voices I usually keep between 80Hz to 11Khz for deep male voices, and about 150Hz to 13KHz for very bright female voices), but fact is not all people can hear everything that's out in nature, and as such I see it as I must choose what's important for the scene and what is just enhancements. And if I can't motivate it at all it has to go anyway.
Take for instance a scene I made recently for a slasher-flick. It's a beautiful scene with two friends sitting in the garden in the middle of nowhere, having a cold one in the calm summer breeze. Summer ambiance is very soft and airy, and as I've already established that they are nowhere near civilization, it's virtually no noise at all. To give it this airy nice feeling, I chosen mostly singing birds and grasshoppers (sounds pretty much as crickets, but we have no crickets in Sweden). I know the birds ought to be audible for anyone except those with the most effed up ears, but I know at least one person who can't hear grasshoppers/crickets at all should his life depend on it. My sound normally is far from overly bright (I've learned that lesson years ago...), but in this case I had to chose between a much brighter and sparser than usual sound as to depict calm and tranquility, or a more sturdy sound that would turn out more doom. And I already had scenes for that. Mildly put (it was a slasher, mind you). Considering people with a limit at about 7KHz, even down to 5KHz, just birds would be pretty lame. Sure one could perhaps had used cicadas or something, but this was supposed to be a Swedish rural summer afternoon with the nearest neighbor no closer than at least a few miles away, and cicadas would make it sound just wrong. So my choice fell to adding a distant wind-chime for texture and space.
You might say, in this case, that I tweaked the scene to suit hearing-impaired people, but fact is I didn't. Not as such, though it is indeed an important parameter. I modeled it after known limitations keeping it fully enjoyable for everyone, but my emphasis was actually still in those hearing frequencies at least up to 10KHz, preferably up to 15KHz (though this scene actually had a spectrum exceeding 22KHz in some elements). It's pretty rare though that I have to consider modeling the range this extremely, most projects I make are often urban, and most of those in the wilderness wouldn't hurt from a little distant wind-noise, and as such I could theoretically make an entire movie without ever needing to consider placing something important with fundamentals above 5KHz for any other reason than to add texture. Despite that, we must always make a choice, and that choice will have consequences. One can make an entire movie keeping within the boundaries of limited hearing, and it will sound pretty good for everyone (provided it's well done). It will be fast, and it will be safe, but it will not shine. One can also keep it within the boundaries, but in a more artistic way. Films like Bourne Ultimatum, Saving Private Ryan, and Wall-E are good examples of movies sounding amazing without really having any treble, where the sound post-team has taken a more coarse way, which works well with cinema without tampering with quality. Different choices makes different sounds, not necessarily meaning one is better than the other, just different. Myself, I love really high-frequency treble, but I'm not overly fond of general sharpness. Thus, fundamentally I work exactly as I did as a producer, especially when I worked with African and Latin American Ethno and Industrial; I try and maintain a firm base for everyone to enjoy, with lots of treats in the extremes for those who can enjoy them. Unless it's for TV, of course. I see no point in working too hard with extremes that almost guaranteed will get completely lost in the mangling of countless (pointless?) extra filters and processors. This post is all about my philosophy when mixing and designing for unaltered fullrange media like DVD and BD, and to some extent cinema.