this woman could hear perfectly as a child until she contracted typhoid. the treatment left her profoundly deaf. she works for the charity which helped fund the research and says she would volunteer for an patient trials. >> i would like the opportunity to hear again. to know in the future if i have kids, i'll be able to hear them. >> reporter: many questions remain, does the hearing improvement last. the gerbils were followed up for ten weeks. and is it safe? the research in the general nature is encouraging but these uncertainties mean patient trials using these cells are still several years away. fergus walsh, bbc news. >> they tested 18 gerbils, they say that patients could receive cell therapy for hearing loss in clinical trials in just a few years. this out of the journal of nature which is very prestigious and respected.