In the first case, the exact one-to-one correspondence may be lost (for example, some phoneme may be represented by a digraph instead of a single letter), but the "regularity" is retained: there is still an algorithm (but a more complex one) for predicting the spelling from the pronunciation and vice versa.
ai versus aï in French This is often due to the use of an alphabet that was originally used for a different language (the Latin alphabet in these examples) and so does not have single letters available for all the phonemes used in the current language (although some orthographies use devices such as diacritics to increase the number of available letters).
Korean hangul has changed over the centuries from a highly phonemic to a largely morphophonemic orthography.
[citation needed] Japanese kana are almost completely phonemic but have a few morphophonemic aspects, notably in the use of ぢ di and づ du (rather than じ ji and ず zu, their pronunciation in standard Tokyo dialect), when the character is a voicing of an underlying ち or つ.
The Russian orthography is also mostly morphophonemic, because it does not reflect vowel reduction, consonant assimilation and final-obstruent devoicing.
In order to maintain a phonemic orthography such a system would need periodic updating, as has been attempted by various language regulators and proposed by other spelling reformers.
Moreover, in many other words, the pronunciation has subsequently evolved from a fixed spelling, so that it has to be said that the phonemes represent the graphemes rather than vice versa.
Systems like IPA can be used for phonemic representation or for showing more detailed phonetic information (see Narrow vs. broad transcription).
English, for example, does not distinguish phonemically between aspirated and unaspirated consonants, but other languages, like Korean, Bengali and Hindi do.
The sounds of speech of all languages of the world can be written by a rather small universal phonetic alphabet.