A diphone is a pair of phonetic sounds that are adjacent to each other in a verbal sequence. Linguists use the diphone as a tool to evaluate language and its uses. The diphone is a small part of a greater set of tools for examining and classifying the features any given language.
One important aspect of the diphone is its distinction from a similar language element called a diphthong. The diphthong is a combined sound that contains two or more vowel components, where a diphone is two separate sounds, including either vowels or consonants, that are placed next to each other. Another element that is similar to the diphone is the triphone. Triphones are composed of three phonetic sounds. Both diphones and triphones are often used in algorithms for natural language processing, where technology tries to either receive or communicate sound according to the technical use of these sound elements in language.
Through identifying diphones correctly, linguists and other experts can attain many different goals. One is to document any changes to the language in terms of dialect or popular use. Another would be to examine the exact use of phonetic subsets relative to others, for example, in comparing the preferred sounds in different languages.
Some scientists and others approach the use of diphones in an extremely technical way. This involves looking at all of the theoretical possible permutations for diphones in a language. In a technical evaluation, the possibilities for diphones would be exponential, since any phoneme, or phonetic element, can be placed next to another. The important thing to note about this is that almost all languages have restrictions on what phonemes are pronounced consecutively, so that in reality, the maximum number of diphones used is less than the theoretical number.
In looking at all of the diphones in a particular language, linguists can learn a lot more about that particular tongue. For example, in English, diphones are separated into several major categories. One category is voiced versus voiceless, where some phonetics have a voiced sound, like "b" and others do not, like "p".
Aside from voiced versus voiceless phonetics, diphones can also include either bilabial phonetics, pronounced with both lips, alveolar phonetics, where the tongue is near the roof of the mouth, and many other phonetic types. In addition, consonants often feature plosive phonetics, a specific kind of oral stop, as well as fricatives and sibilants, which rely on forcing air through the throat.