<i>What’s the solution? Multi-Band Compression (MBC), a technique that’s been used by the $6 billion hearing aid industry to solve this specific problem.<p>An MBC uses intelligent design instead of a one-size-fits-all method. With the right data about your hearing pattern, it can mash the full sound into your range so that you get all the information you need.</i><p>Audio engineer here. That is patently untrue. MBC is a super-useful technique and is indeed helpful for mitigating hearing loss in relatively transparent fashion, but it does not and cannot bring sounds from outside someone's audible hearing range back within it. It will dynamically rebalance incoming audio in inverse proportion to the degree of hearing loss within a set of frequency ranges, but many kinds of sensorineural hearing loss involve the death of cilia cells (the tiny hairs thatvibrate at particular frequencies, much like the bins of of an FFT) which can result in a total loss of perception at or above certain frequencies.<p><a href="http://en.wikipedia.org/wiki/Sensorineural_hearing_loss" rel="nofollow">http://en.wikipedia.org/wiki/Sensorineural_hearing_loss</a><p>To 'mash the full sound into your range' requires a technique known as frequency shifting, but that's problematic because it destroys the harmonic relationships of the incoming material and sounds disorienting, at best.<p>In any case, I think the illustration of the bear on the tricycle is absurdly simplistic and makes me wonder to what the degree the pp designers really grasp the underlying concept. A much more appropriate parallel would have been to show an image with a severe Gaussian blur, which more closely parallels the actual experience of hearing loss in terms of both empirical measurement (higher frequencies tend to be more severely attenuated in cases of induced hearing loss) and subjective experience (blurring hinders edge detection, which is analogous to transient detection in audio, and which has a large role in speech intelligibility.<p><a href="http://en.wikipedia.org/wiki/Gaussian_blur" rel="nofollow">http://en.wikipedia.org/wiki/Gaussian_blur</a><p>If you're struggling with hearing loss, then you should really, <i>really</i> consult an audiologist, work out the basis of your hearing loss (which is sometimes as simple as impacted earwax), and work out a treatment strategy. If you're suffering from degenerative hearing loss then listening to overly-compressed music could actually accelerate it, and listening on headphones or earbuds (many of which bias the sound for increased impact) could also contribute to the problem. It's a truism in the pro audio world that most people are <i>awful</i> at self-measurement and tend to over-equalize in the absence of proper experimental control protocols.<p>I apologize for the rather negative tone of the post; I appreciate the people at SoundFocus are trying to provide people with something useful and helpful at minimal cost, by leveraging the pretty good audio hardware in their phone. However, hearing loss tends to be a one-way thing, and I think that offering a product to that market without a clinician on the team is a bad idea. There's a lot more to being an 'audio ninja' than understanding the fundamentals of DSP.