Phonetics and phonology
The most obvious aspect of language is speech. Speech is not essential to the definition of an infinitely productive communication system, such as is constituted by a language. But, in fact, speech is the universal material of human language, and the conditions of speaking and hearing have, throughout human history, shaped and determined its development. The study of the anatomy, physiology, neurology, and acoustics of speaking is called phonetics; this subject is dealt with further below (see Physiological and physical basis of speech). Articulatory phonetics relates to the physiology of speech, and acoustic phonetics relates to the physics of sound waves—i.e., their transmission and reception.
Phonetics covers much of the ground loosely referred to in language study as pronunciation. But, from a rather different point of view, speech sounds are also studied in phonology. Every language makes use of a very wide range of the articulations and resultant sounds that are available within the human vocal and auditory resources. Each language uses a somewhat different range, and this is partly responsible for the difficulty of learning to speak a foreign language and for speaking it “with an accent.” But mere repertoires of sounds are not all that is involved. Far fewer general classes of sounds are distinctive (carry meaning differences) in any language than the number of sounds that are actually phonetically different. The English t sounds at the beginning and end of tot and in the two places in stouter are all different, though these differences are not readily noticed by English speakers; and, rightly, the same letter is used for them all. Similar statements could be made about most or all of the other consonant and vowel sounds in English.
What is distinctive in one language may not be distinctive in another or may be used in a different way; this is an additional difficulty to be overcome in learning to speak and understand a foreign language. In Chinese and in several other languages loosely called tone languages, the pitch, or tone, on which a syllable is said helps to distinguish one word from another: ma in northern Chinese on a level tone means “mother,” on a rising tone means “hemp,” and on a falling tone means “to curse.” In English and in most of the languages of Europe (though not all—Swedish and Norwegian are exceptions), pitch differences do not distinguish one word from another but form part of the intonation tunes that contribute to the structure and structural meaning of spoken sentences.
Languages differ in the ways in which consonant and vowel sounds can be grouped into syllables in words. English and German tolerate several consonants before and after a single vowel: strengths has three consonant sounds before and three after a single vowel sound (ng and th stand for one sound each). Italian does not have such complex syllables, and in Japanese and Swahili, for example, the ratio of consonant and vowel sounds in syllables and in words is much more even. Speakers of such languages find English words of the sort just mentioned very hard to pronounce, though to an Englishman they are perfectly natural, natural in this context meaning “within the sounds and sound sequences whose mastery is acquired in early childhood as part of one’s mother tongue.”
All these considerations relating to the use of speech sounds in particular languages fall under the general heading of phonology, which may be defined as the sound system of a language; phonology is often regarded as one component of language structure.