An early stage of language development in which infants combine consonant and vowel sounds in experimental ways is known as

Cooing refers to the early vocalizations made by infants, usually occurring around 6 to 8 weeks of age, where they produce soft vowel sounds like "oo" and "ah." This stage precedes babbling and does not involve the combination of consonants and vowels, making it distinct from the babbling stage.

Semantics deals with the meaning of words and phrases in language. It is a higher-level cognitive process that occurs after the foundational stages of sound production, such as babbling, and is not directly related to the experimental sound combinations of infants.

Holophrases are single words used by infants to convey a whole idea or sentence, typically emerging around 12 months of age. This stage follows babbling and involves using a single word to express complex meanings rather than combining sounds.

Pragmatics refers to the social aspects of language use, including the context and manner in which language is used in communication. It is a more advanced skill that develops later and is unrelated to the initial sound experimentation seen in babbling.