Dissimilation and Haplology in Phonetics

Dissimilation is a general term in phonetics and historical linguistics for the process by which two neighboring sounds become less alike. Contrast with assimilation. According to Patrick Bye, the term dissimilation "entered the field [of phonology] in the 19th century from rhetoric, where it had been in use to describe the variation in style required for good public speaking" (The Blackwell Companion to Phonology, 2011).

Dissimilation and Haphology

As discussed below, one type of dissimilation is haplology—a sound change involving the loss of a syllable when it's next to a phonetically identical (or similar) syllable. Perhaps the best known example is the reduction of Anglaland in Old English to England in Modern English. Haplology is sometimes called syllabic syncope. (The counterpart of haplology in writing is haplography—the accidental omission of a letter that should be repeated, such as mispell for misspell.)

The Phonetics of English

• Elision
• Language Change
• Pronunciation
• Segment and Suprasegmental
• Sound Change
• What Is the Correct Pronunciation of "February"?
• Word Boundaries

Examples of Dissimilation

• "[An] example of dissimilation is the substandard pronunciation of chimney as chimley, with the second of two nasals changed to an [l]. The ultimate dissimilation is the complete loss of one sound because of its proximity to another similar sound. A frequent example in present-day standard English is the omission of one of two [r] sounds from words like cate(r)pillar, Cante(r)bury, rese(r)voir, terrest(r)ial, southe(r)ner, barbitu(r)ate, gove(r)nor, and su(r)prised."
  (John Algeo and Thomas Pyles, The Origins and Development of the English Language, 5th ed. Thomson, 2005)

Dissimilation of Liquid Consonants

• ​"Consider [an] example of dissimilation of liquid consonants that took place when the suffix -al attached to some Latin nouns to make adjectives. The regular suffixation process gives us pairs like the following: orbit/orbital, person/personal, culture/cultural, electric/electrical. However, when an /l/ precedes the ending anywhere in the root, the ending is changed from -al to -ar as a result of dissimilation: single/singular, module/modular, luna/lunar." (Kristin Denham and Anne Lobeck, Linguistics for Everyone. Wadsworth, 2010)

Assimilation v. Dissimilation

• ​"Assimilation is far more common than dissimilation; assimilation is usually regular, general throughout the language, though sometimes it can be sporadic. Dissimilation is much rarer and is usually not regular (is sporadic), though dissimilation can be regular. Dissimilation often happens at a distance (is non-adjacent) . . .." (Lyle Campbell, Historical Linguistics: An Introduction. MIT Press, 2004)

Causes and Effects of Haphology

• ​"We say that assimilation and dissimilation are changes that result in an increase or decrease, respectively, in the degree of phonetic similarity between two segments. It is tempting to think that such changes in the one segment are somehow caused by the phonetics of the other, and for generations that is actually how the matter has usually been presented. . . . But this is a confusion of cause and effect. It is true that the effect of the change is a net increase/decrease of similarity between two segments, but it is begging the question (to say the least) to assume that the degree of similarity is also somehow the cause of the change. The fact is that very little is known of the actual mechanisms of these changes, commonplace as they are." (Andrew L. Sihler, Language History: An Introduction. John Benjamins, 2000)

Haplology

• "Haplology . . . is the name given to the change in which a repeated sequence of sounds is simplified to a single occurrence. For example, if the word haplology were to undergo haplology (were to be haplologized), it would reduce the sequence lolo to lo, haplology > haplogy. Some real examples are:

(1) Some varieties of English reduce  library to 'libry' [laibri] and  probably to 'probly' [prɔbli].
(2)  pacifism pacificism (contrast with  mysticism mysticism, where the repeated sequence is not reduced and does not end up as  mystism).
(3) English  humbly was  humblely in Chaucer's time, pronounced with three syllables, but has been reduced to two syllables (only one  l) in modern standard English. (Lyle Campbell,  Historical Linguistics: An Introduction, 2nd ed. MIT Press, 2004)

The Haphology Effect

• The haplology effect can often be heard in the casual pronunciation of each of these words: February, probably, regularly, and similarly. 
• "The words library and necessary, especially as spoken in Southern England, are often heard by foreigners as libry and nessary. But when they repeat the words as such, they do not sound right, since there should be a lengthened r and s, respectively, in those words. It shows that foreigners notice the beginning stages of haplology in those words, when there is as yet no complete haplology." (Yuen Ren Chao, Language and Symbolic Systems. Cambridge University Press, 1968)