Dissimilation
In phonology, particularly within historical linguistics, dissimilation is a phenomenon whereby similar consonants or vowels in a word become less similar. In English, dissimilation is particularly common with liquid consonants such as /r/ and /l/ when they occur in a sequence. Examples. Dropped initial /r/ in /r..r/ sequence (r-Deletion). When a sound occurs before another in the middle of a word in rhotic dialects of English, the first tends to drop out, as in "" for "berserk," "" for "surprise," "" for "particular", and "" for "governor" – this does not affect the pronunciation of "government," which has only one , but English  government tends to be pronounced "", dropping out the first n. In English, "r"-deletion occurs when a syllable is unstressed and may drop out altogether, as in "" for "deteriorate" and "" for "temperature," a process called haplology. When the is found in , it may change to . (, "" → "February," which has been explained by phonotactic factors or alternatively by morphological analogy with more common sequences such as "January". "nucular", which may have arisen through an analogous process) Dissimilation of /l..l/ to /r..l/. An example where a relatively old case of phonetic dissimilation has been artificially undone in the spelling is English  colonel, whose standard pronunciation is (with the r sound) in North-American English, or in RP. It was formerly spelt "coronel" and is a borrowing from French "coronnel", which arose as a result of dissimilation from Italian "colonnello". Causes. There are several hypotheses on the cause of dissimilation. According to John Ohala, listeners are confused by sounds with long-distance acoustic effects. In the case of English , rhoticization spreads across much of the word: in rapid speech, many of the vowels may sound as if they had an "r". It may be difficult to tell whether a word has one  source of rhoticity or two. When there are two, a listener might wrongly interpret one as an acoustic effect of the other, and so mentally filter it out. This factoring out of coarticulatory effects has been experimentally replicated. For example, Greek "pakhu-" (παχυ-) "thick" derives from an earlier "*phakhu-." When test subjects are asked to say the "*phakhu-" form in casual speech, the aspiration from both consonants pervades both syllables, making the vowels breathy. Listeners hear a single effect, breathy voiced vowels, and attribute it to one rather than both of the consonants, as they assume the breathiness on the  other syllable to be a long-distance coarticulatory effect, thus replicating the historical change in the Greek word. If Ohala is correct, one might expect to find dissimilation in other languages with other sounds that frequently cause long-distance effects, such as nasalization and pharyngealization. Types. Dissimilation, like assimilation, may involve a change in pronunciation relative to a segment that is adjacent to the affected segment or at a distance, and may involve a change relative to a preceding or a following segment. As with assimilation, anticipatory dissimilation is much more common than lag dissimilation, but unlike assimilation, most dissimilation  is triggered by "non"-contiguous segments. Also, while many kinds of assimilation have the character of a sound law, few dissimilations do; most are in the nature of accidents that befall a particular lexical item. Anticipatory dissimilation. Anticipatory dissimilation at a distance (by far the most common): Anticipatory dissimilation from a contiguous segment (very rare): Lag dissimilation. Lag dissimilation at a distance (fairly common): Lag dissimilation from a contiguous segment (very rare): Paradigmatic dissimilation. When, through sound change, elements of a grammatical paradigm start to conflate in a way that is not easily remedied through re-wording, the forms may dissimilate . For example, in modern Korean the vowels and are merging for many people in the capital Seoul, and concurrently the second-person pronoun 네 'you' is shifting to 니 to avoid confusion with the first-person pronoun 내 'me'. Similarly, it appears that English "she," historically "heo", may have acquired its modern "sh" form through dissimilation from "he", though it is not clear whether the mechanism was idiosyncratic sound change (palatalization) of "heo", or substitution of "heo" with the feminine demonstrative pronoun "seo".