Hearing aid technology is very evolved. They went programmable DSP decades ago, and now we have bionic cochlear implants where the brain learns to sort out signals derived from a microphone. The good products and clinical techniques are not cheap, so many people make do with primitive devices to which you refer.

Earbuds, OTOH, are cost driven tech that is so inferior they degrade hearing from long term use. Besides the potential for physiological damage from listening too loud and distorted, earbuds can re-wire spatial hearing until normal hearing in rooms deteriorates. This is especially true of overprocessed or synthesized sounds, synthesized spatialization, digitally compressed files like MP3, AAC and streaming formats on YouTube, Vimeo, etc.

The standard model of hearing has been over-simplified for 85 years. Since the Blumlein experiment ,which is the basis of stereo as we know it, spatial hearing has been assumed to be a process of two scalar signals. This has failed to explain many documented examples of human hearing proficiency.

We now know that vector information is transmitted to the basilar membrane, which explains for example why humans can separate conversations in a noisy, crowded reverberant room far better than DSP or human decoding of stereo, surround and binaural recordings.

Further, it has been shown that trained individuals can surpass the Fourier uncertainty principle by a factor of ten, which was believed to be theoretically impossible. There are also aural observations that appear to violate the Nyquist criterion, specifically the claims that some people can hear obvious differences between CD quality and HD audio.

99+% of the population can’t hear this difference. This deficiency is a symptom of training to distorted content like pop music and iTunes; bad audio systems like iPhone/iPod circuits and earbuds; and the noise pollution of urban and suburban environments. $13 BlueTooth devices are going to make hearing worse yet.