I was thinking a telepathic race won't need hearing to know when a predator is near, since they would sense another being's emotion/thoughts long before it comes near them. slightly harder to explain would be cases like natural events, like volcano eruption, land slide, etc. but how often do those things happen? I don't think our hearings were evolved for those things. we don't have the senses like the animals do to feel the oncoming of an earthquake, for example. so it's not too hard to imagine that a telepathic race did not evolve hearing for natural disasters. they probably train themselves to tune to the natural world and sense the panic of the animals around and react accordingly.
Hearing evolved because it had many uses, including the ability to detect approaching storms, floods, and other dangers. It makes no sense to assume that an evolutionary process would be selective in its reasons for developing a specific sense. Evolution doesn't happen by conscious design. A trait develops to serve one purpose, and if it happens to provide another advantage, it can then evolve further to increase that advantage. The first creatures to evolve rudimentary hearing probably did develop it as an elaboration upon the ability to sense vibrations through their bodies. Vibration is vibration, regardless of the source.
And of course no species evolves in isolation. A humanoid is the end result of hundreds of millions of years of evolution from earlier multicellular forms. On Earth, hearing probably evolved before brains per se, certainly long before any kind of consciousness arose. So it's likely that if telepathy evolved on any given alien world, it would be long, long after hearing evolved. So the question isn't whether a telepathic race would need to evolve hearing; the question is whether having telepathy would make it unnecessary for that species to keep its ancestral ability to hear. On the whole, I'd say no; hearing is too useful for many functions beyond communication within one's own species, so telepathy would not justify the complete loss of hearing.
However, I gather from what Dave said above that only some members of the species in Troublesome Minds are deaf, not the entire species. That's more justifiable. It means that if deafness arose as a mutation in some of the population, it would be compensated for by the ability to communicate telepathically with others who could hear and could instantly share what they heard. So deaf individuals in such a species would not be weeded out by death to the same extent they'd be in a non-telepathic species, and thus congenital deafness would be able to spread further through the population -- not as an adaptive trait that would become dominant over time, but as a relatively harmless mutation that simply wouldn't be eliminated.