Within the different levels of linguistic analyses, one branch cannot be completely separated from the other. To the contrary, there are frequent interfaces.In this case the two structural levels of language which interact are Morphology and Phonology.

Morpho(pho)nology or Morphophonemics is concerned with the systematic realization of morphemes and how they depend on their respective environment.
Whereas Phonology deals with speech sounds and pronunciation in a particular language; Morphonology involves lexical and grammatical information, combined with phonological details.\\ Morphonology is a branch of linguistics which mainly occupies the combinatorial phonic modifications of morphemes.

Furthermore Morphonology tries to set up rules which apply to phonological elements but only under certain morphological conditions.

One example is:

"capacious" vs. "capacity"

- [eI] in "capacious" alternates with [a] in "capacity" (the alternation is not restricted to this specific pair, compare "veracious" vs. "veracity".

- Thus it concerns the vowels [aI] and [a], not the form "capac-" as a whole.

- However, it applies to words with a certain morphological structure, basically derived from Latin. Therefore, in many accounts, it is morphophonological, not simply phonological.

Morphonology contains:

  1. a study of the phonemic differences between allomorphs of the same morpheme.
  2. the distribution of allomorphs in one morpheme.
  3. the structure of a language in terms of morphophonology.
    Morphemes are the basis of Morphonology.

The word “Independently” for example has four morphemes:

  • "In"
  • depend
  • “ent”
  • “ly”

The part "depend" is the basis for the word "independently". The other three morphemes are derivational affixes.
Allomorphs are different kinds of realization of a morpheme. Plural endings present this sort of Allomorphs, for example.
Furthermore Morphonology studies the alternation series which serve a morphological function.
Examples of a morphophonological alternation in English include these distinctions:

  • Plurals "-es" and "-s", as in "bus, buses" vs. "bun, buns".
  • Plural of "-f" is "-ves", as in "leaf, leaves"
  • Different pronunciations for the past tense marker "-ed".