The study of pronunciation of words is called

Concept: Different branches of language study describe sounds in different ways. Orthoepy is the study of the accepted, standard pronunciation of words — it tells you how a word ought to be spoken. It is prescriptive: it deals with what counts as correct pronunciation, often in relation to spelling.

Application: The stem asks specifically for the study of the pronunciation of words. That definition matches orthoepy exactly — "orthoepy" comes from Greek orthos (correct) + epos (speech), literally "correct speech", i.e. the study of how words should be pronounced.

Contrast — why the near-misses do not fit:

• Phonetics studies the physical speech sounds themselves — how they are articulated, their acoustic properties, and how they are heard. It is descriptive and broader than the pronunciation of particular words, so it is the close distractor but not the term for the standard pronunciation of words.

• Speech is the general act of speaking, not a field of study, so it cannot be the name of this discipline.

• Voice refers to the sound a person produces, not the study of how words are pronounced.

Result: the study of the pronunciation of words is orthoepy.