Here is an interesting discussion I had in my class recently. Phonological rules can be classified by the kind of process they involve. Here are the seven major types of phonological rules/processes with examples.
1. Assimilation – phonological process in which a sound changes to resemble a nearby sound and can occur both forward and backward.
Ex. The prefix in- where sometimes it appears as in– and others as im-. In front of bilabial words, in– becomes im-. This also happens across word boundaries, like in between pronounced with an m.
2. Dissimilation – phonological process in which two close sounds changes to become less alike.
Ex. Manner dissimilation where a stop becomes a fricative when followed by another stop. The word sixth is pronounced sikst, /sθ/ becomes /st/.
3. Insertion – phonological process in which a sound is added to a word.
Ex. Voiceless stop insertion where between a nasal consonant and a voiceless fricative, a voiceless stop with the same place of articulation as the nasal consonant is inserted. In English, many say hampster instead of hamster, a /p/ is added.
4. Deletion – phonological process in which speech sounds disappear from words.
Ex. English is a fast/common speech language, so vowels can be deleted to make the word one syllable, and easier to pronounce in a fast manner. Police becomes plice, and friendship is said as frienship.
5. Metathesis – phonological process in which sounds switch places in the phonemic structure of a word.
Ex. To make words easier to pronounce and understand, letters are switched. Two historical examples include Old English (brid and aks) becoming Modern English (bird and ask).
6. Strengthening (fortition) – phonological process in which a sound is made stronger.
Ex. Aspiration is where voiceless stops become aspirated when they occur at the beginning of a stressed syllable. Top is said with as h.
7. Weakening (lenition) – phonological process in which a sound becomes weaker.
Ex. The definition of flapping is before a stressed vowel and before and unstressed vowel where the sound is pronounced with articulation resembling a flap. The word kitty is an example where the alveolar stop is realized as /r/.
I think deletion is more important and more pertinent in my own life. To pronounce every consonant and vowel, in every single word, would be tiring and time consuming. As an English speaker, time is money. Being able to delete certain letters to make words easier to pronounce as one-syllable structures is useful. When I write fast, my handwriting becomes sloppy in my attempt to get down all of the information in my head. I believe the same rule applies to speech.