Focus (phonetics)

Speakers can indicate that a certain syllable is important by making a pitch movement on that particular syllable. This accent-lending pitch movement places the syllable (or the word or word group) in focus. The focus domain covers the string of speech sounds that together form the important part.
Broad focus vs narrow focus: the focus domain can be broad or narrow, and this is exemplified in the following questions and answers (focus domain is shown between brackets).
(1) Question: Did you see a grey dog or a cat? Answer: I saw [a grey DOG].
(2) Question: Did you see a grey dog or a grey cat? Answer: I saw a grey [DOG].
In (1), the focus domain covers the word group "a grey dog", whereby the pitch accent is placed on "dog". In (2) the focus domain is narrowed to "dog", as this is the only important word in the word group.

Link

Utrecht Lexicon of Linguistics

References

• Chomsky, N. 1981. Lectures on Government and Binding, Foris, Dordrecht.