Abstract: (intro paragraph in lieu of abstract) If we had machines that could hear as humans do, we would expect them to be able to easily distinguish speech from music and background noises, to pull out the speech and music parts for special treatment, to know what direction sounds are coming from, to learn which noises are typical and which are noteworthy. Hearing machines should be able to organize what they hear; learn names for recognizable objects, actions, events, places, musical styles, instruments, and speakers; and retrieve sounds by reference to those names. These machines should be able to listen and react in real time, to take appropriate action on hearing noteworthy events, to participate in ongoing activities, whether in factories, in musical performances, or in phone conversations.