More information on irrigation, agronomic practices carried out and weather conditions will be helpful. I think generally frost injury causes this kind of problem in barley. The Freezing temperature during crop growth stages will have negative impact on plants (especially when barley is damaged before the 2-leaf stage or at heading or soft dough stage). Particularly freezing during heading or pollination stage resulting in sterility, white heads, white awns and water soaking and shriveling at the base of the head.
Most of the time the damaged heads looks normal but the anthers will die since they are more sensitive to freeze damage when compare to other plant parts (damaged anthers appear white and desiccated instead of normal light green or yellow color).