A phoneme is a basic unit of sound used to build a language. All spoken words are made up of one or more individual phonemes. Few languages use all the sounds available to human speech. Instead, most pull from a selection of standard phonemes to create many thousands of words. Alphabets, including that of English, do not always have a one-to-one correspondence between phoneme and letter.
Linguists often differentiate between the possible sounds a human can make and the specific sounds that affect word meaning. They typically use the term, phones, to describe speech sounds in general, and phonemes to refer to sounds that are used to build a language. For the most part, languages do not utilize all the possible phones that the human mouth can create.
Phonemes make up the constituent parts of spoken words. Linguists have formulated a system of symbols to graphically represent phonemes. Most languages have been assigned a list of standard phonemes that represent the most common sounds used in speech. These standard sounds are combined in a variety of ways to create different words.
For the most part, a phoneme is tied to the meaning of a word. As a result, if a phoneme changes, the word’s meaning typically changes as well. For example, if the first sound in the word, bat, is changed from /b/ to /p/, the word becomes pat and takes on a new meaning.
In many languages, each letter corresponds with a phoneme. For example, in the English word bit, each letter represents a phoneme, /b/, /I/, /t/. In many languages, including English, this one-to-one correspondence between letter and phoneme is not standard for all words.
Many English words contain digraphs, which are phonemes that are represented by more than one letter. For example, the first sound in thing, is th represented by the single phoneme symbol, /ð/. The final sound is ng, represented by the symbol, /ŋ/.
Often languages like English allow for two letters to be used interchangeably for one phoneme. For example, the letters c and k may both be used to represent the sound, /k/. The first sounds in the words kit and cap are both /k/.
Sometimes, the pronunciation of a word can differ depending on the dialect of the speaker. Different dialects may pronounce different sounds, or phones, for the same phoneme. If two phonemes can be exchanged in a word without altering the word’s meaning, then linguists say that these two sounds are called allophones.