3.3.1 Contrastive distribution

　 If sounds appear in the same environment, they are said to be in contrastive distribution. Typical contrastive distribution of sounds is found in minimal pairs and minimal sets. A minimal pair consists of two words that differ by only one sound in the same position. Sip and zip, tip and dip, map and nap, etc, are all minimal pairs. Minimal sets are more than two words that are distinguished by one segment in the same position. The words beat, bit, bet and bat form a minimal set. The vowels in them are separate phonemes.

　 The overwhelming majority of the consonants and vowels represented by the English phonetic alphabet are in contrastive distribution. There are a few segments which are not. For example, you cannot find minimal pairs involving /h/ and //. /h/ never occurs at the end of words (except for words borrowed from other languages) and // never appears word-initial. It is also difficult to find minimal pairs in English that involve the sound //, which is mostly found in words borrowed from French, such as garage, mirage, azure. Nevertheless, these sounds are distinctive in terms of phonetic features. They are therefore separate phonemes.