In linguistics, assimilation and dissimilation are phonological terms. They mean the process of assimilation or assimilation of sounds in the neighborhood. That is, these are concepts that are completely opposite in meaning.
Assimilation is such a linguistic phenomenon in the Russian language, when within a single word or their combination, sounds are likened to each other. It has several causes. The main reason that assimilation occurs is that articulation of adjacent sounds is connected. As a result of such proximity, some of them acquire the properties of others. Assimilation is a phenomenon that has several manifestations. As a rule, several of its types are distinguished:
1) Accommodation. This is when the movement of the vocal apparatus when pronouncing one sound adapts to the articulation of another. This often happens with cacuminal consonants. These are sounds, pronouncing which a person directs the tip of his tongue up. For example, in the word “laugh it off” “t”, when pronouncing, adapts to “w”.
2) Coarticulation. It manifests itself as the mutual influence of sounds in the neighborhood. For example, what happens to the consonant that faces the vowels “o” or “u”? It is extinguished, since the movements necessary for pronouncing two adjacent sounds are performed simultaneously.
3) Actually assimilation. This is such a phenomenon when sounds located close or in the neighborhood are likened to such an extent that they cause a change in the phonemic composition of a particular word. It can be considered a consequence of the two previous processes, since it has more visible results.
However, it will be wrong to consider assimilation only from the point of view of physiology. The fact is that from the standpoint of articulation there are always two, and not just one, pronunciation variants. For example, you can take the word "expand". It is pronounced both purely: ra (ssh) it, and ra (ssh) it.
Depending on which particular sound of the two combining is likened, distinguish:
- regressive assimilation. In this case, the second sound is positionally stronger and the first is articulated to it. This type of assimilation in Russian speech is very common. For example, in the word “fairy tale” the sound “z” becomes deaf after “k”;
- progressive assimilation. In this case, the first sound is stronger, and the next is likened to it. In Russian, this phenomenon does not occur.
Assimilation can also be partial and complete. It depends on the results of the comparison. If the sounds that are combined in a phrase or in a word differ from each other only in one way, then their complete assimilation takes place. For example, in the word “give” the sounds “t” and “d” differ only in terms of voiced-deafness, therefore “t” is completely likened to “d” and the word is pronounced as “o (dd) at”. If there are differences in some other properties, then assimilation is only partially accomplished. For example, in the word “beat off” the sounds “d” and “t” differ not just in sonority-deafness, but also in hardness-softness, in the peculiarities of the movement of the speech apparatus when they are pronounced.
Assimilation in English has its own characteristics. In it, it is manifested not so much by the loss of sounds or by their assimilation, as by a change in the place in which the barrier is formed. For example, the consonants "s, z, n, t", whose pronunciation is performed on the alveoli, before some other consonants move to the tooth gap. This simplifies the utterance of previous sounds.
It is clear that assimilation is a phonetic process. That is why over time it becomes the cause of varying degrees of shifts in phonology. The presence of assimilation in a word or its absence leads to the fact that the same sounds in it can have different signs.