This site traces the history of English phonemes. A phoneme is not a sound, but instead a class of sounds. Different speakers make different actual sounds when articulating the same phoneme, but competent speakers of the language recognize these different sounds as representing "the same thing." It is perhaps easiest to think of a phoneme as a rule for articulating a sound of the spoken language. Different speakers of English will produce different actual sounds when articulating the word the, but the vocal organs of all physiologically normal speakers will perform similar motions.
Linguists think of the phoneme as the elementary unit of any natural language. That is, it is possible to think of any utterance in a natural language as being constructed by the successive addition of phonemes to make words and then sentences.
We indicate that we are writing phonemes by enclosing the symbol for the phoneme within diagonal marks: /b/, /p/, /a/. When a phoneme (or other linguistic form) is "unattested"--that is, when we have no written records attesting to the form--we precede the symbol with an asterisk. Thus, we might write "Germanic */a/," indicating that we suppose that such a phoneme existed in proto-Germanic, but that we have no written records to prove our conjecture.
The phonemes of any given language function by contrasting systematically with each other. That is, a linguist knows that there are two different phonemes when there is a "minimal pair": there must be two different phonemes /b/ and /p/ represented by the letters b and p in the English words bat and pat, because speakers of English hear bat and pat as two different words.
The phonemic structure of English has changed over time, so that it makes sense to talk about a "history" of English phonemes. These changes in the language are usually referred to as "sound-changes," but the connection of actual sounds with phonemes is, as we have said, not simple. This site follows the normal custom of dividing the history of the English language into four periods: Old English (450-1100), Middle English (1100-1500), Early Modern English (1500-1800), and Present-Day English (1800-present).
Colors (red for OE, blue for ME, violet for EME, and black for PDE) will be used throughout the site to distinguish the phonemes of the different periods from each other. Often, "the same symbol" (e.g., /e/) will be used to write phonemes from different periods. Thus, there is an OE /e/ and a ME /e/, but these are different phonemes, and presumably would have sounded different. (In this case, the OE phoneme is a "short vowel," whereas the ME phoneme is a "long vowel.")
The phonemic structure of English at the four traditional periods is indicated by tables labelled "Consonants" and "Vowels" that contain a specification of the phonemes of the language at the period in question.
Branching from these tables, each phoneme of OE, ME, EME, and PDE has a page in the site. On that page, a table indicates the sources of the phoneme, the changes affecting the phoneme, and the so-called "reflexes" of the phoneme--that is, what the phoneme produced at the next chronological stage of the language. Thus, it is possible to navigate through the pages in order to trace the history of any particular phoneme.
The sound-changes affecting phonemes are collected and divided according to period in the section of the site called "Sound-Changes."
English spelling often obscures the phonemic structure of the language. The "Spelling" section of the site allows one to start with a particular spelling, and to determine which phoneme or phonemes that spelling was likely to indicate at any of the four stages of English.
The "Phonology" section of the site presents an elementary treatment of phonology--that is, the study of how speech-sounds are produced by the human vocal apparatus.
"Useful Links" leads to Web pages that might be helpful for those who want to explore the subject further.