Phonetic flats
Puzzle variations in which sounds (technically, phonemes) are the basic unit instead of letters. An example of a phonetic beheadment: ONE = quest, TWO = west; a phonetic charade: ONE = lox, TWO = myth, WHOLE = locksmith; a phonetic curtailment: ONE = cute, TWO = queue. In a phonetic curtailment, TWO can be longer than ONE; what counts is the sequence of sounds, not the sequence of letters. In fact, the greater the change in spelling, the more interesting the base. When discussing phonetic flats, we sometimes refer to the regular, letter-based flats as orthographic.
A flat is phonetic if (1) the whole base works phonetically, and (2) some part does not work orthographically. No flat is labeled phonetic if it can also work in its entirety as a letter-based puzzle. Mite, rite could be a first-letter change or a first-sound change, but it is considered a first-letter change. Mite, right has to be a first-sound change.
The underlined letters, as pronounced in the following words, stand for single sounds: loud, chin, whale, joke, sing, coin, ship, thin, this, vision, copper. These sounds are indivisible. On the other hand, these represent two sounds: few and curable. The y and oo sounds are separate. These decisions are based on the MW pronunciation guides. (In particular, MW treats \r\ (the first sound in “run”) and \ər\ (the first sound in “earn”) as different phonemes, so we do likewise, although we merge them in phonetic consonantcies.)
Modern pronunciation varies widely; you’re likely to encounter phonetic flats that don’t work in your speech. They are still legal and valid as long as MW substantiates their pronunciation. (For example, LeXman’s spoonergram cheesy grin, greasy chin works in Indiana but not in Massachusetts.)
The MW dictionaries also indicate where stresses fall in a word, but we ignore this for phonetic flats; only the sequence of phonemes matters. For example, new ditty and nudity is a valid homonym.
These pronunciation variations are common enough to be acceptable without comment in flats:
\w\ = \hw\. For most Americans, where and wear are homonyms.
For many Americans, T and D have the same sound between two vowels if the second vowel is unstressed; latter and ladder are homonyms.
\ä\ = \ȯ\. For most Americans, bother rhymes with father. For a minority, cot is a homonym of caught.
Before a vowel sound, \ār\ = \er\ = \ar\. Many Americans pronounce Mary and merry the same, and a large minority pronounce marry the same as the other two. Online MW is not consistent on this point; NI3 explains it. Phonetic flats based on this pronunciation are not tagged “NI3 pronunciation”.
Schwa: \ə\ = \i\ when unstressed. For many, language and languid are a last-sound change.
Most phonetic flats are labeled as “phonetic” and then the orthographic type; for more information, see the rest of the puzzle’s name. There are a few exceptions: instead of “phonetic letter”, we say “sound”: e.g., scuba, caboose is a reversed sound shift. Instead of “phonetic bigram”, we say biphoneme. Also, the heteronym was invented to be the orthographic analogue of the homonym.