What is the smallest unit of sound that can affect a word's meaning called?

The correct answer, phonemes, refers to the smallest distinctive units of sound in a language that can change the meaning of a word. For example, altering the initial sound in the words "bat" and "cat" results in two different meanings, despite the remainder of the words being identical. Phonemes are fundamental to understanding spoken language and play a crucial role in phonics, which is essential for reading and language acquisition.

Understanding phonemes is essential in educational psychology, particularly in the context of language development and literacy. Recognizing how these sounds contribute to word formation aids in teaching children how to read and phonetic awareness, which are vital skills in language learning. Other options in the question—such as language system, communication, and anxiety disorders—do not directly relate to the specific function of sound units in affecting word meanings, making phonemes the most precise term for this concept.