Assimilation is a phonological process where a sound changes to become more similar to a neighboring sound. This can occur in various ways, such as voicing assimilation, place assimilation, or manner assimilation.

Coalescence is a phonological process where two adjacent sounds merge into a single sound. This can occur when two sounds are similar in articulation or when one sound is weakened or lost.

Deletion is a phonological process where a sound is lost from a word or phrase. This can occur for various reasons, such as simplification of pronunciation or the influence of neighboring sounds.

Metathesis is a phonological process where two sounds switch places within a word or phrase. This can occur due to errors in speech production or as a regular sound change in a language.

Substitution is a phonological process where one sound is replaced with another sound. This can occur for various reasons, such as ease of pronunciation, historical sound changes, or dialectal variations.

Addition is a phonological process where a sound is added to a word or phrase. This can occur for various reasons, such as the insertion of a vowel to break up a consonant cluster or the addition of a prefix or suffix.

Lenition is a phonological process where a sound becomes weaker or is lost altogether. This can occur due to changes in pronunciation over time or as a result of assimilation or other phonological processes.

Fortition is a phonological process where a sound becomes stronger or more pronounced. This can occur for various reasons, such as emphasis, clarity of pronunciation, or historical sound changes.

Devoicing is a phonological process where a voiced sound becomes voiceless. This can occur for various reasons, such as assimilation to a neighboring voiceless sound or as a regular sound change in a language.

Voicing is a phonological process where a voiceless sound becomes voiced. This can occur for various reasons, such as assimilation to a neighboring voiced sound or as a regular sound change in a language.

Centralization is a phonological process where a sound moves towards a more central position in the mouth. This can occur for various reasons, such as ease of pronunciation or assimilation to neighboring sounds.

Palatalization is a phonological process where a sound is pronounced with a more front position in the mouth, often involving the raising of the tongue towards the palate.

Velarization is a phonological process where a sound is pronounced with a more back position in the mouth, often involving the raising of the tongue towards the velum.

Labialization is a phonological process where a sound is pronounced with a more rounded shape of the lips. This can occur for various reasons, such as ease of pronunciation or assimilation to neighboring sounds.

Nasalization is a phonological process where a sound is pronounced with a more nasalized quality, involving the lowering of the velum to allow air to pass through the nasal cavity.