1. Assimilation: One sound becomes more like the neighboring sound. For example, in English, the plural ending "-s" is pronounced as /z/ after voiced sounds like /b/ (e.g., "dogs") and as /s/ after voiceless sounds like /p/ (e.g., "cats"). Here, the /s/ assimilates to the voicing of the preceding sound.
2. Elision: One sound is completely dropped. For example, in English, the word "cannot" can become "can't," where the /t/ sound is elided.
3. Metathesis: Two sounds swap places. For example, in some dialects of English, "ask" is pronounced as "aks."
4. Fusion: Two sounds combine to create a new, single sound. For example, in some Romance languages, the Latin sounds /k/ and /s/ have coalesced into the single sound /ʃ/ (as in the Spanish word "chisme" from Latin "chisma").
Examples of Coalescence in Different Languages:
* English: The pronunciation of "walked" as /wɔkt/ instead of /wɔlkəd/.
* French: The pronunciation of "il" (he) + "a" (has) as "il a" (he has).
* Spanish: The pronunciation of "cielo" (sky) as /θjelo/ instead of /sjelo/.
Note: Coalescence is a complex phenomenon that can be affected by factors such as phonological context, historical development of a language, and individual speaker variation. It is an important aspect of linguistic change and can lead to significant differences in pronunciation between languages and dialects.