Claude, I've not heard or read anything that would suggest that vitamin A(
retinol) could reverse hearing loss due to nerve damage(usually caused by 
high sound levels, but also occassionally due to severe infection).  The 
types of cells that vitamin A regulates are the general epithelial cells 
and these cell types are not the ones that function in the ear hearing 
process.  The hair cell nerve-like epithelial cells in the ear may respond 
to vitamin A during cellular differentiation(embryogenesis) but I don't 
know if they are still capable of responding in adults.  If they are 
capable of responding with new hair growth, this would be a very major 
breakthrough in hearing loss.  With all of the medical interest in vitamin 
A, it would not be too surprising if a clinical study was done using 
vitamin A to reverse hearing loss.  But with only a news announcement to go 
on(and this type of communication is notoriously bad), I can't comment on 
your question anymore than I already have.  If one study has been done, 
more will need to follow to firm up a link between vitamin A and hearing 
loss if there really is one.