We have successfully developed some oral histories with group members. These are personal, so I have not shared them here, but we did have some fun working on them!
You may like to trial some of the ideas and techniques outlined in the source documents below – simplifying as necessary and ensuring a good fit for the subject. In our group we kept things simple by using an iPad and Audacity [free] software to edit the results.
Some time ago I gave a Dementia Friends talk at the Imperial War Museum (IWM) and took some time out to have a listen to some of their 33,000 oral histories/sound archive. Most of it is available online (see below), but if you pop-in to the IWM they can help you source more material even more quickly. Give it a try.