Paralanguage is a component of meta-communication that may modify or nuance meaning, or convey emotion, such as prosody, pitch, volume, intonation etc. It is sometimes defined as relating to nonphonemic properties only. Paralanguage may be expressed consciously or unconsciously. The study of paralanguage is known as paralinguistics, and was invented by George L. Trager in the 1950s, while he was working at the Foreign Service Institute of the Department of State. His colleagues at the time included Henry Lee Smith, Charles F. Hockett (working with him on using descriptive linguistics as a model for paralanguage), Edward T. Hall developing proxemics, and Ray Birdwhistell developing kinesics. Trager published his conclusions in 1958, 1960 and 1961. His work has served as a basis for all later research, especially those investigating the relationship between paralanguage and culture (since paralanguage is learned, it differs by language and culture). A good example is the work of John J. Gumperz on language and social identity, which specifically describes paralinguistic differences between participants in intercultural interactions. The film Gumperz made for BBC in 1982, Multiracial Britain: Crosstalk, does a particularly good job of demonstrating cultural differences in paralanguage, and the impact these have on relationships.
Paralinguistic information, because it is phenomenal, belongs to the external speech signal (Ferdinand de Saussure's parole) but not to the arbitrary conventional code of language (Saussure's langue).