1. Historical linguistics Considers the ways languages change through time and some of the factors that influence those changes. Synchronic VS diachronic Old English (forgyf) Middle English (foryeue) Early modern English (forgiue) Contemporary English (forgive)

2. Sound change assimilation; one sound became more like another: wolf-wulvas. Dissimilation: two similar sounds became less like another: fifth-fift Deletion: deletion of unstressed word final: nose (nδzә) VS (noz) Insertion: athlete (æθәlit) VS (æθlit)

3. Family tree Languages change in regular, recognizable ways. Similarities among languages are due to a genetic relationship among those languages The theory uses the terms parent, daughter, and sister E.g. French and Spanish are sisters

4. Wave theory Recognizes the gradual spread of change throughout a dialect, language or group of languages. It is much like a wave expands on the surface of a pond from the point where a pebble has been tossed in.

5. Wave theory Some speakers use the mid-low back rounded lax vowel ('open o'), while others use the low back unrounded vowel. Note that the speakers from Austin, mainland North Carolina, Harker's Island (off the coast of North Carolina), and New York City have an 'open o' vowel in "talk", while the speaker from Kansas uses the low back unrounded vowel.

6. Dialect map AustinAllophone of //KansasAllophone of //Mainland North CarolinaAllophone of //Harker's Island, NCAllophone of //New York CityAllophone of //

8. Unconditional Sound Change Monopthongization: a change of diphthong to a simple vowel sound consisting of a vowel followed by a glide, a monophthong. Midle English: rude /riwdә), rule /riwlә/, new (niwә) Dipthongization: a change of a simple vowel sound to a complex one. Eg. house /hŭs/ VS /huws/

9. Unconditional Sound Change Metathesis: a change in the order of sounds: ask /æks/ VS /æsk/ Raising/Lowering: Changes in the height of tongue in the production of sounds. Noon /nōn/ VS /nŭn/ Raising: ō > ŭ Backing/fronting: alteration in the frontness or backness of the tongue in the production of sounds: e.g. /a/ became /æ/ as in path, glass, asks.