earshot       
noun [ U ] uk/ˈɪə.ʃɒt/ us/ˈɪr.ʃɑːt/
 听力可及的范围;可听距离
the range of distance within which it is possible to be heard or to hear what someone is saying
  I don't think you should say anything while the boss is still in/within earshot. 我觉得,老板还没走远你应该什么也别说。 
 Wait till she's out of earshot before you say anything. 等她走远听不见了,你再说不迟。 
 Synonym: hearing