Comparing distributions with minimal pairs
In addition to the individual distribution of a single phone, we are also often interested in the relative distribution of two phones. If they have overlapping distributions, such that there are at least some environments where they both can occur, the two phones are said to contrast with each other, and thus, they have contrastive distribution.
This relates to the concept of minimal pair from Section 3.8. Recall that for signed languages, a minimal pair is two signs that have the same articulation except for one parameter. These two signs can be said to contrast with each for that parameter. We can adapt this concept to words in spoken languages.
For example, in English, the phones [p] and [k] occur in many of the same environments, creating pairs such as [pɪl] pill and [kɪl] kill, [lɪp] lip and [lɪk] lick, and [spɪl] spill and [skɪl] skill. Each of these pairs is a minimal pair that have all the same phones in the same order, except for one position. So [pɪl] pill and [kɪl] kill both have the form [▁ɪl], with [p] in one word and [k] in the other.
The existence of just one such minimal pair is all it takes to prove that two phones have contrastive distribution, so minimal pairs play an important role in figuring out the distribution of phones in a language and how they may be grouped into the same or different phonemes.
However, in many cases, it may be difficult or even impossible to find minimal pairs. In English, the phone [ʒ] is the rarest consonant and has a limited distribution, occurring in words like [ruʒ] rouge, [ɡərɑʒ] garage, [vɪʒn̩] vision, and [mɛʒr̩] measure. It is almost never word-initial in English, except in some proper names (perhaps most famously, Hungarian-American actress Zsa Zsa Gabor) and in the neologism [ʒʊʒ] zhoozh ‘improve the appearance of someone or something with a small change’. This makes it difficult to find minimal pairs where [ʒ] is a crucial phone, especially when comparing it to another relatively rare phone like [ʃ], though there are a few examples of minimal pairs for [ʒ] and [ʃ] involving unusual or rare words, such as [əluʒn̩] allusion versus [əluʃn̩] Aleutian and [mɛʒr̩] measure versus [mɛʃr̩] mesher.
Near-minimal pairs and nonce words
But if no minimal pairs can be found, we usually have to rely on near-minimal pairs instead. A near-minimal pair looks almost like a minimal pair, except there are one or more additional differences elsewhere in the word besides the crucial position. For example, the English pair [plɛʒr̩] pleasure and [prɛʃr̩] pressure form a near-minimal pair for [ʒ] and [ʃ]. In the position of interest, we have [ʒ] versus [ʃ], which seem to be contrastive because nearly all of the rest of the phones are the same in both words, except for [l] versus [r], which prevents these words from being a true minimal pair.
While a single minimal pair is very powerful, a single near-minimal pair is not. We may have simply stumbled upon a weird example where the apparent meaningless difference is actually relevant to the distribution of the phones we are interested in. We cannot immediately determine whether or not a given near-minimal pair is useful, so it is important to find multiple examples. As we collect more near-minimal pairs, we can be more confident that the small differences are incidental rather than crucial to the distribution of the phones in question.
This is where speaker competence can also be useful, by asking them to evaluate nonce words, which are words that we make up for one-time use, such as for linguistic experimentation. We can construct nonce words that fill in minimal pair gaps, and if speakers agree that the nonce word is a valid hypothetical word of the language, then we can be more sure that the phones in question do in fact contrast with each other.
For example, rather than looking for more near-minimal pairs for [ʒ] and [ʃ], we could instead take an existing word with [ʒ] in it, like [beʒ] beige, then create a nonce word that is the same, except replacing [ʒ] with [ʃ], giving us a pair like [beʒ]-[beʃ]. Then we could ask English speakers whether the nonce word [beʃ] could be used as a completely different word with a different meaning from [beʒ]. Most speakers would agree, so we would be reasonably sure that [ʒ] and [ʃ] do indeed contrast with each other, despite not having a true minimal pair of actual existing English words.
Depending on the structure of the language and what resources we have access to, we may use one or more of these three tools (minimal pairs, near-minimal pairs, nonce words) to determine whether two phones contrast with each other. We would also need to do this work for every pair of phones in the language, but in some cases, we may get lucky, and there may be minimal triplets, minimal quadruplets, or even larger minimal n-tuplets.
For many speakers, English beet, bit, bait, bet, bat, but, bot, bought, boat, and boot form a minimal 10-tuplet (a decuplet!), showing simultaneously that the ten vowels [i], [ɪ], [e], [ɛ], [æ], [ʌ], [ɒ], [ɔ], [o], and [u] all contrast with each other. This cuts down on the work needed to demonstrate patterns of contrast in the language. But in many languages, even minimal pairs can be hard to find, so finding near-minimal pairs and testing nonce words may be the only options.
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