Answer:
Phonology.
Step-by-step explanation:
Phonetics and phonology are two complementary branches of linguistics and their primary domain of study are sounds. Phonetics studies sounds as acoustic units, independent of their use and meaning.
The concern of phonology, on the other hand, are those same sounds as elements of a system that is a language. Phonology examines the way that sounds (phonemes) are used and combined in order to create meaning and transmit intelligible messages.