informants

noun
  1. 1

    One who relays confidential information to someone, especially to the police; an informer.

  2. 2

    A native speaker who acts as a linguistic reference for a language being studied. The informant demonstrates native pronunciation, provides grammaticality judgments regarding linguistic well-formedness, and may also explain cultural references and other important contextual information.

Source: https://en.wiktionary.org/wiki/informant, https://en.wiktionary.org/wiki/informants