An ELT Glossary : Pitch / Key

• Definition : Pitch (or key) is the relative height of speech sounds as perceived by the listener. 

• Example : In English, asides will be perceived as being lower than the surrounding discourse, while a new topic in a news broadcast will start at a higher level than the ending of the previous item. This is not necessarily true in other languages and can lead to learners failing to pick up "clues" as to how the various items in the discourse relate to each other.

• Pitch is decided by the rate of vibration of the vocal cords. The faster the rate of vibration, the higher the pitch.