Distinctive feature in the context of "Voice (phonetics)"

In phonology, vowel harmony is a phonological process in which vowels assimilate ("harmonize") to share certain distinctive features. Vowel harmony is often confined to the domain of a phonological word, but may extend across word boundaries in certain languages.

Generally, one vowel will trigger a shift in other vowels within the domain, such that the affected vowels match the relevant feature of the trigger vowel. Intervening segments are common between affected vowels, meaning that the vowels do not need to be next to each other for this change to apply, classifying this as a "long-distance" type of assimilation. Common phonological features that define the natural classes of vowels involved in vowel harmony include vowel backness, vowel height, nasalization, roundedness, and advanced and retracted tongue root.

In historical linguistics, a sound change is a change in the pronunciation of a language. A sound change can involve the replacement of one speech sound (or, more generally, one phonetic feature value) by a different one (called phonetic change) or a more general change to the speech sounds that exist (phonological change), such as the merger of two sounds or the creation of a new sound. A sound change can eliminate the affected sound, or a new sound can be added. Sound changes can be environmentally conditioned if the change occurs in only some sound environments, and not others.

The term "sound change" refers to diachronic changes, which occur in a language's sound system. On the other hand, "alternation" refers to changes that happen synchronically (within the language of an individual speaker, depending on the neighbouring sounds) and do not change the language's underlying system (for example, the -s in the English plural can be pronounced differently depending on the preceding sound, as in bet[s], bed[z], which is a form of alternation, rather than sound change). Since "sound change" can refer to the historical introduction of an alternation (such as postvocalic /k/ in the Tuscan dialect, which was once [k] as in di [k]arlo 'of Carlo' but is now [h] di [h]arlo and alternates with [k] in other positions: con [k]arlo 'with Carlo'), that label is inherently imprecise and must often be clarified as referring to either phonemic change or restructuring.

In phonetics, length or quantity is a feature of sounds that have distinctively extended duration compared with other sounds. There are long vowels as well as long consonants (the latter are often called geminates).

Many languages do not have distinctive length. Among the languages that have distinctive length, there are only a few that have both distinctive vowel length and distinctive consonant length. It is more common that there is only one or that they depend on each other.

The phonological word or prosodic word (also called pword, PrWd; symbolised as ω) is a constituent in the phonological hierarchy. It is higher than the syllable and the foot but lower than intonational phrase and the phonological phrase. It is largely held to be a prosodic domain in which phonological features within the same lexeme may spread from one morph to another, from one clitic to a clitic host, or from one clitic host to a clitic.

The phonological word and grammatical word are non-isomorphic. Sometimes what counts as a word for the phonology can be either smaller or larger than what counts as a word for syntactic purposes. A clear case of this mismatch is compound words, which count as two words phonologically, but one in the syntax.

In historical linguistics, transphonologisation (also known as rephonologisation or cheshirisation, see below) is a type of sound change whereby a phonemic contrast that used to involve a certain feature X evolves in such a way that the contrast is preserved, yet becomes associated with a different feature Y.

For example, a language contrasting two words */sat/ vs. */san/ may evolve historically so that final consonants are dropped, yet the modern language preserves the contrast through the nature of the vowel, as in a pair /sa/ vs. /sã/. Such a situation would be described by saying that a former contrast between oral and nasal consonants has been transphonologised into a contrast between oral and nasal vowels.

In phonology, a natural class is a set of phonemes in a language that share certain distinctive features. A natural class is determined by participation in shared phonological processes, described using the minimum number of features necessary for descriptive adequacy.