Alkatran said:
But if it's just an ear problem, then it's entirely possible they can imagine (really simple) sounds.
It's like tribdog said; they can try to imagine what sound must be like but the chance of it coming anywhere close is about nill.
Imagine there is a sense you don't have, called, say, the sense of troob. The exterior organs of troob are the eyebrows. To you eyebrows are ornamental, and maybe they help keep dust out of your eyes, but other people explain to you that they are constantly "troobing" the environment around them with their eyebrows and receive all kinds of information about it that is unavailable from sight, hearing, smell, and touch.
Now, as you grow up you would go through many periods of wondering what it was like to be able to troob. You would often ask people if they could explain it to you in terms of the senses you
do have, but, of course, they can't because troobing is as different from the senses you do have as sight is to touch, or any other sense.
Now, they can explain to you that troobing is nothing less than a direct reaction to the Earth's magnetic field, and they can show you a compass to prove it has a magnetic field, but that explains nothing.
Once in a while you meet a more patient person who tries to explain that troobing doesn't provide specific information about direction and location per se, but creates a "depth and separation and resonance" that enriches people's experience of location. "It's roughly, roughly analagous to the different way differences in air moisture make a person feel or the way sound changes when moving from outdoors to inside affects you, except it's much more intense and is triggered by smaller differences in body position. And the experience is such that it's important to people and they would feel much diminished if they lost the ability.
Now, you can take all that and imagine what it might be like to troob, but, really, anything you come up with is about guarranteed to be wrong.