Hearing, or auditory perception, is the ability to perceive sounds by detecting vibrations, changes in the pressure of the surrounding medium through time, through an organ such as the ear. The academic field concerned with hearing is auditory science.
Speech is the vocalized form of communication used by humans and some animals, which is based upon the syntactic combination of items drawn from the lexicon. Each spoken word is created out of the phonetic combination of a limited set of vowel and consonant speech sound units (phonemes). These vocabularies, the syntax that structures them, and their sets of speech sound units differ, creating many thousands of different, and mutually unintelligible, human languages. The vocal abilities that enable humans to produce speech also enable them to sing.
Within a bony labyrinthean cave, Reached by the pulse of the aërial wave, This sibyl, sweet, and Mystic Sense is found, Muse, that presides o'er all the Powers of Sound.
Abraham Coles, Man, the Microcosm; and the Cosmos, p. 51.