What defines phonemes?

Phonemes are defined as the smallest units of sound in a language that can distinguish meaning. They are the distinct speech sounds that can change the meaning of words when altered; for instance, changing the phoneme 'p' in "pat" to 'b' forms the word "bat," which has a different meaning. This highlights the essential role of phonemes in language and speech.

Other options describe related but different concepts. Letters used in spelling refer to the written form of phonemes, but they do not capture the subtle distinctions of sounds themselves. Written symbols that represent sounds refer to graphemes, which are not synonymous with the auditory characteristics of phonemes. Lastly, rhythm and intonation pertain to prosody, which involves the patterns of stress and intonation in speech, not the individual sounds of phonemes. Thus, identifying phonemes specifically revolves around their role as distinguishable speech sounds rather than their representation or the way language is structured rhythmically.