informant

An informant or consultant in linguistics is a native speaker or member of a community who acts as a linguistic reference for a language or speech community being studied. The informant's role is that of a senior interpreter, who demonstrates native pronunciation, provides grammaticality judgments regarding linguistic well-formedness, and may also explain cultural references and other important contextual information to researchers from other cultures studying the language. Linguistic informants, especially those who frequently work with linguists, may play a greater than usual role in the researcher's work, and other titles such as consultant or coauthor may be used to acknowledge and accurately reflect that contribution.