[Tronz]

I know that the frequencies of earphone BA's try to cover as much of the area between 20hz and 20khz as possible. But, how are hearing aide BA's tuned? Minus the fact that they're sometimes to tuned for a specific persons hearing losses, are the BA's automatically tuned to show a higher sensitivity between the 1 - 4khz range where the human voice mainly lies? Do hearing aide BA's cover bass frequencies or very high treble? Or are hearing aide BA's essentially the same thing as earphone BA's just not ever piggy backed on top of each other with crossovers for a multi-driver solution?