What I didn't fully realise until I spoke to our accessibility team was 
that there are so many degrees of hearing impairment. So there are many 
strategies that can be taken depending on the specific conditions.
Signing, and the recording of that signing, is certainly one approach, but 
only suitable for those that can use it and it's very expensive. It also 
requires a certain amount of planning (ie booking a signer).
One of the things about podcasting that makes it such a wonderful medium 
potentially is its immediacey in certain situations - recording and 
releasing a podcast can be rich and rapid. When it's used for deliverying 
recorded lectures I can see that it is possible to plan various 
approaches, but in my view the really interesting applications for 
podcasting don't fit tidily into that planned lecture slot.
This is why I'm looking to find/put together a document that guides 
podcasters through the issues and options so that they can apply the 
guidance to their ideas and conditions. I have contacted TechDis and I 
think that it's a good idea to explore this with them.