Minimal pairs
A phoneme is the smallest meaningful unit of sound in a particular language. The key word in this definition is “meaningful.” There are many sounds we can make with our mouths, including coughing, grunts, and other noises, but only certain sounds have meaning for us in language. In order to determine if a sound has meaning to us, we set up a pair of words in which the only difference is one single sound. For example, let us take the word “bit,” or [bɪt]. By writing these symbols between square brackets [ ] we signal that we are using the International Phonetic Alphabet, or IPA. The square brackets are used to show that these sounds represent the pronunciation of the individual speaker. Let us now pair the word [bɪt] with the word “pit”, in IPA [pɪt]. Because we can distinguish a contrasting difference when we hear the words [bɪt] and [pɪt], that is, because we recognize these as two distinct words, we can determine that [b] and [p] must have a meaningful difference between them. In other words, these two sounds [b] and [p] are each phonemes in English. Since they are phonemes, we can write them between slashes: /b/ and /p/. Two words that differ by only a single phoneme are called minimal pairs.
On the other hand, we can take the word “bit” [bɪt] again, but this time, we can pronounce the initial consonant with a heavy breath of air. This is an “aspirated” [b], from the word “aspiration,” which means breathing. We can signify it in IPA by adding a superscript h like this: [bh]. Now let’s make a minimal pair, one with the word “bit” said in the usual way, [bɪt], and one with the word said with an aspirated b, [bhɪt]. In spite of the differences in the pronunciation of the first consonant, an English speaker will not hear these two pronunciations as two different words. [bɪt] and [bhɪt] both represent the same word “bit,” and therefore they fail the minimal pair test. Therefore [b] and [bh] are not two distinct phonemes. They are two non-meaningful variants, called allophones, of the phoneme /b/.
The set of phonemes that we will discuss on the following pages are those of English only. Every language has its own set of phonemes. There are languages, like Hindi, in which [b] and [bh] are different phonemes; other languages have no phonemic distinction between [p] and [b]. The number of phonemes in different languages can also vary widely. Humans have the ability to produce about 600 different consonant sounds and 200 vowel sounds, but English only uses about 24 consonant phonemes and 15 vowel phonemes, for a total of 39 distinct meaningful sounds. Ubykh, an extinct language from the Caucasus, had 86 phonemes–84 consonants and only 2 vowels! Hawaiian, on the other hand, has only 13 distinct phonemes, 8 consonants and 5 vowels. It does not matter how many phonemes a language has; what matters is that the set of phonemes function as a system, where those sounds and only those are meaningful and capable of carrying information.
