chapter 11.3: phonemes
A phoneme is the smallest meaningful unit of sound. The key word in this definition is meaningful. Although speech is continuous, as we listen to someone speaking, we are able to break the words and phrases into individual segments, to which we ascribe meaning. For example, we analyze the word “pit” as composed of three distinct segments, each of which is a meaningful phoneme: /p/, /ɪ/, and /t/, or simply /pɪt/. To signify that we are talking about phonemes and using the IPA, we write the symbols between slashes / /. When we discuss actual pronunciation, regardless of phonemic status, we use square brackets [ ].
Minimal pairs
In order to determine if a sound is a phoneme, we can set up a pair of words in which the only difference is one single sound. For example, take the word “pit” again, written in IPA as [pɪt], and let us pair it with the word “bit”, in IPA [bɪt]. These words differ by only a single sound, the first one; there is the minimal amount of difference between the two words. Thus, we call the set a minimal pair. Because we as English speakers can distinguish the utterances [pɪt] and [bɪt] as two distinct words, we can determine that /p/ and /b/ must have a meaningful difference to us. This difference allows us to establish that /p/ and /b/ are both phonemes in English. Another way to think of the word “meaningful” is as a contrastive difference. The sound /p/ has a contrastive difference from other sounds such as /b/ or /t/ or /f/.
We can establish other phonemes of English in the same way, by taking a word like “pit,” and changing it by one sound at a time. Take “pit,” and change the first sound to “b”: “bit.” Now change the first sound to “h”: “hit.” Now change the vowel to the “ee” sound: “heat.” Now change the last sound to “d”: “heed.” Now change the first sound to “m”: “mead.” Now change the vowel to the long “a” sound: “made.” And so on. You can see here that the spelling changes in various unexpected ways, but if we write these words in IPA it is clearer that only one sound is changing at a time: [pɪt] ~ [bɪt] ~ [hɪt] ~ [hit] ~ [hid] ~ [mid] ~ [med]. This method can be used to build an inventory of phonemes of a particular language. This short chain of minimal pairs allows us to determine that the following are phonemes of English: /p b h ɪ i t d m e/.
It may seem obvious that all these sounds are “meaningful,” but there are many different ways to pronounce sounds that have no meaningful distinction between them. Besides all the grunts, burps, squeaks, laughs, etc. that we can make with our mouths, we have many different types of sounds we can make that are not phonemes. For example, pronounce the word “bid” with a long, drawn-out vowel. We could try to convey this vowel in English spelling as “biiiiiiiid,” or we could write it in IPA by adding the symbol [ː], which is used to indicate a lengthened vowel: [bɪːd]. Now let’s contrast them as a minimal pair: [bɪd] and [bɪːd]. These are two very different ways to say the word, and yet the word remains “bid.” Therefore, these two vowels fail the minimal pair test, which tells us that [ɪː] and [ɪ] and not two distinct phonemes in English. They are simply two non-meaningfully different ways to say the phoneme /ɪ/. These variations within a phoneme are called allophones, a concept that will be discussed in more detail later.
One more example of non-meaningful variants within a phoneme will suffice. Again, take the word “bid,” but this time 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]. If we contrast “bid” said in the usual way with the word with an aspirated b: [bɪd] and [bhɪd], we find that the pair do not create two distinct words and therefore the sounds fail the minimal pair test. Therefore there is no contrastive difference between [b] and [bh] and they are not two distinct phonemes. Instead, they are simply two allophones of the phoneme /b/.
Every language has its own set of phonemes. There are languages in which the length of a vowel changes the meaning of a word. This was the case in English 1000 years ago, when the word “ac” with a short vowel [ɑk] meant “but” and the word “ac” with a long vowel [ɑ:k] meant “oak tree.” Thus, in Old English /ɑ/ and /ɑ:/ were two distinct phonemes, whereas now in Modern English they are two allophones of the same phoneme /ɑ/. Similarly, there are languages like Hindi in which /b/ and /bh/ are two distinct phonemes. 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. (If you are interested in how babies begin to distinguish the phonemes of their own language, see “Does an 11-week-old know what English sounds like,” from which the figures above on the total number of consonant and vowel sounds humans can make were taken).