oral history
noun /ˌɔːrəl ˈhɪstri/
  /ˌɔːrəl ˈhɪstri/
[uncountable]- the collection and study of historical information using sound recordings of interviews with people who remember past events口述历史(用访谈录音方法);口述历史学 - Oral history is the oldest form of history there is.口述历史是最古老的历史形式。 
- Oral history enables us to take account of those many aspects of history that are not recorded in documents.历史的许多方面未记录在案,是口头流传的历史使我们注意到这些层面。 
 
- Oral history is the oldest form of history there is.