In phonetics, intonation is the variation of the [[fundamental frequency]] of speech sounds used to convey the speaker's attitude and emotions, focus on part of a sentence, distinguish between statements and questions, or regulate the flow of the discourse. Intonation can change the meaning of a sentence or phrase by emphasizing different words or expressing different emotions, such as surprise, excitement, or sarcasm. Intonation patterns vary across languages and dialects and are influenced by factors such as cultural background, regional accent, and individual speaking style. In many languages, intonation is characterized by [[pitch contour]].