So a parametric EQ boost is not what's happening. The image below shows graphs for hearing loss of 0dB, 20dB, 40dB and 60dB HL.
View attachment 37760
With age, the effects are most noticeable at the threshold of hearing for the quietest sounds and with declining sensitivity to high frequencies (both of which are part of typical audiometric tests). But the changes are more fundamental, and have to do with perception of loudness overall (and this kind of testing is done only in research settings).
What's experienced is level-dependent sensitivity changes. As you get older the filter characteristics of the ear change and broaden. Because of this, more frequencies will fall into the same critical band and so certain ranges will feel louder than before. Once mapped, it will appear as if the equal-loudness curves have been compressed. The SPL-to-phon ratio is what's being affected.
Briefly, if you play bandpassed noise which stays within a single critical band you will experience a specific loudness level. You can broaden or narrow the bandwidth of the noise and compensate the amplitude per frequency such the overall power level and consequently the perception of loudness will remain the same. However, once the noise bandwidth is broadened beyond the critical band, even after compensating for amplitude, you will experience a subjective increase in loudness.
So with playback current hardware applies the same level of gain to each frequency without level compensation. Given the compression of loudness curves, it means that the dynamic changes in music are much too broad. This means that older folks may prefer more compressed music given that the level changes will stay within a more narrow band on average. This may also explain the preference for tube electronics (not because of added distortion, which can affect loudness perception as well, particularly for the highs) but because tubes dynamically compress signals.
@JoachimStrobel is entirely right when he says that the industry should move toward creating equipment that is able to compensate for subjective loudness at different volume levels, much of which will include modifying existing parts to make sure they are rugged enough to handle individual perceptual requirements.
What this all translates to is that you'll need greater overall boost at low levels to achieve the same relative loudness across the spectrum and experience relatively normal hearing at louder levels, although the distance between what constitutes "low" and "normal" has shrunk.