Onbin (Japanese "euphony") is a set of sound changes that occurred in Early Middle Japanese around the end of the eighth century to the beginning of the tenth century, first attested in written texts of the Heian period. Onbin changes affected certain consonant-vowel sequences in non-word-initial position, causing them to become replaced with either a single vowel sound (as in , from earlier ) or a single consonant sound (as in , from earlier ). (In some cases, this also caused a change in the pronunciation of the preceding vowel or following consonant, as in the development of original to in .) Onbin played a role in diversifying the syllable structure of native Japanese words by creating heavy syllables that ended in two vowels or in a vowel followed by a consonant.
Historical onbin changes did not occur systematically, and some sequences could yield multiple outcomes. The non-deterministic nature of the historical sound changes is exemplified by doublets showing different outcomes of the same original form, such as (without onbin) versus (with u-onbin) from original , or (with N-onbin) versus (with u-onbin) from original . However, some onbin changes have come to be grammaticalized in the conjugation of Japanese verbs: as a result, certain verbs systematically display an "onbin stem" before certain suffixes in standard modern Japanese. The formation of these onbin stems varies between dialects.
Sound changes The outcomes of onbin changes were bound moraic phonemes pronounced in the same syllable as the preceding vowel. Four distinct outcomes can be identified based on modern Japanese kana spellings: the two high vowels and the two moraic consonants : , currently spelled as い in hiragana and イ in katakana (romanized as ) , currently spelled as う in hiragana and ウ in katakana (forms long vowels romanized as or ) or N-onbin, currently spelled as ん in hiragana and ン in katakana (romanized as syllable-final ) or Q-onbin, currently spelled as っ in hiragana and ッ in katakana (romanized as consonant doubling)
divides i-onbin and u-onbin into two categories based on whether they were originally nasalized, and so recognizes six possible outcomes of onbin in the Early Middle Japanese period: .
The core set of onbin changes affected non-word-initial syllables that contained the consonants followed by . (In this context, represents a consonant phoneme derived from Proto-Japonic *p: it was some kind of bilabial consonant in Early Middle Japanese, although its exact pronunciation is debated. The syllables transcribed here as are sometimes alternatively romanized as "fa fi fu fe fo" or "ha hi fu he ho": the use of "h" is anachronistic in terms of Early Middle Japanese pronunciation, but corresponds to the modern pronunciation of the kana that were used to spell these syllables in historical kana orthography, before Japanese script reform.) Some onbin changes could affect word-final syllables, such as the change of to (as in to 'empress') or to (as in to 'in this way'), and occasionally to , or to or (as in to 'courtier'). In contrast, onbin changes involving seem to be attested only in the middle of words.
These core changes can be summarized as follows:
Core onbin changes Source Outcome (modern hiragana/katakana) Examples vowel moraic consonant source word vowel moraic consonant pipu u (う/ウ) Q (っ/ッ) nipi₁ + tataputo₁- niutatauto- nittatatto- ki i (い/イ) yoki₁ yoi ku u (う/ウ) takume₂ taume bi ũ > u (う/ウ) N (ん/ン) aki₁ + bi₁to₂ akiũdo akindo bu ũ > u (う/ウ) *sabusabu-si saũzaũ-(si)- gi ĩ > i (い/イ) tugi₁te tuĩde gu ũ > u (う/ウ) N (ん/ン) kagupasi kaũbasi kanbasi mimu ũ > u (う/ウ) N (ん/ン) ko₁ + mi₁tipi₁ + muka(si) koũdipiũga kondipingasi ninu N (ん/ン) sinitekinu + kaki sindekingai
Subscript numbers distinguish syllables that were different in Old Japanese, as indicated by man'yōgana, but that merged in the transition to Early Middle Japanese. considers it likely that onbin changes affected only and not (and so took place before their merger), whereas disagrees. Since syllables with /i₂/ were less frequent, the relevant evidence is limited, and there is a possible case of > in the word , normally derived from Old Japanese tuki₂ "moon, month": Frellesvig argues this could be a folk etymology.
Additional changes When the consonant in the affected sequence was either nasal or prenasalized , onbin produced a nasal output: either a nasalized high vowel or a moraic nasal consonant . These nasal sounds caused following to be replaced with their prenasalized counterparts, . By Late Middle Japanese, the nasalized vowels had merged with , and the change of to after a nasal sound ceased to apply as an automatic process, although it had lasting effects on the form of some inflectional morphemes and lexicalized compound words.
During Late Middle Japanese, vowel sequences ending in (including that derived from earlier ) fused into long vowels (which can be phonologically analyzed as sequences of two identical vowel phonemes in one syllable). If the first vowel was originally or , the resulting long vowel was preceded by a palatal glide . This produced the following outcomes:
Fusion of vowel + U late Early Middle Japanese Late Middle Japanese Modern Japanese
Because of this vowel fusion, words with u-onbin, such as , do not always contain the vowel phoneme in modern Japanese, although they are still spelled with the kana う/ウ (u) because of a convention of spelling long non-phonetically in this context.
In verbs and adjectives
Verb stems
As a result of onbin changes, consonant-stem verbs developed variant "onbin stems" used before certain suffixes (in modern Japanese, the past , gerund , conditional , and representative ). Consonant-stem verbs are those that can be analyzed as having underlying stems that end in a consonant (in modern Japanese, any of ): these verbs take the suffix in the dictionary form, in contrast to vowel-stem verbs, which have stems that end in either or and take the suffix in the dictionary form. In Japanese grammatical terminology, consonant-stem verbs are called verbs, because their inflected forms make use of the five kana that represent the stem-final consonant plus each of the five Japanese vowels (). Verbs with stems ending in show an additional complication: stem-final is deleted before suffixes that start with , since Japanese phonotactics only allow to occur before the vowel . In terms of historical development, verb stems that end in originally ended in the consonant *p.
The onbin stem developed from the Early Middle Japanese infinitive () form, which ended in . When the infinitive form of a consonant-stem verb ended in one of the syllables , it could undergo the onbin sound changes described above. In addition, it came to be possible for to undergo analogous changes in this context: thus, could become (as in > , > ) and could become (as in > ). argues that verbs with stems ending in developed onbin stems purely as a result of the morphological process of analogy, rather than as a result of the same phonetic processes as the other onbin changes.
In modern Standard Japanese, the form of a verb's onbin stem can typically be predicted from the underlying stem-final consonant: give , give (with voicing of the following to in the suffix), gives , and gives (with voicing of the following to in the suffix). Verbs with underlying stems ending in do not show onbin in contemporary standard speech, but instead use () before the relevant suffixes.
Examples of grammatical onbin in verb stems stem consonant onbin type Example verb forms Dictionary Negative Gerundive (original p)
is the only n-stem verb in modern Japanese.
A few verbs have an exceptionally formed onbin stem. For example: the verb (stem ) has an onbin stem in , e.g. , rather than the expected . the verbs and (stems , , originally -, -) have u-onbin stems, e.g. , , rather than the expected . the honorific verbs , , , , and all exhibit an i-onbin stem prior to the polite auxiliary verb , e.g. , , etc., rather than the expected non-onbin form . These verbs have the expected onbin forms before suffixes , , , .
Dialects show some differences in the formation of onbin stems. Some dialects regularly use u-onbin (with fusion of to ) for verb with underlying stems that end in (where standard Japanese has Q-onbin) or verbs with underlying stems that end in (where standard Japanese has N-onbin). Use of u-onbin for verbs with stems that end in (original ) is a feature of dialects spoken in western regions, such as Kansai (including Kyoto) and Kyushu. For example, in the Kyoto dialect the verb (stem ) has the past form , in contrast to standard Japanese . The 17th-century Arte da Lingoa de Iapam by João Rodrigues identified the use of u-onbin in this context as a feature of the Japanese spoken in Kyoto, in contrast to the use of Q in the Kanto dialect. Use of u-onbin for verbs with stems that end in is found on Kyushu and in the far west of Honshu; in contrast, in Kyoto and most of Kansai, these verbs currently show consonantal onbin as in the standard language. For example, in some dialects the verb (stem ) has the gerund form , in contrast to (used in standard Japanese and in the Kyoto dialect). The voicing of the suffix to indicates that these u-onbin forms originally contained nasalized . Use of i-onbin for verbs with stems that end in survives dialectally in some regions, including much of Kansai (although not in Kyoto). Thus, forms such as can occur in place of standard for the gerund of the verb (stem ). Some dialect forms show consonantal onbin in verbs with stems ending in or , where standard Japanese has i-onbin.
The use of onbin stems in inflected verb forms never become normative in literary written Classical Japanese. It is difficult to tell how frequent they were in speech at various historical periods.
, citing , gives the following chronology for the written attestation of onbin in verb forms: to : seen from the late 9th century. to : rarely seen until the mid 10th century, from which point it is found regularly. (original ) to : seen from the first half of the 11th century. to : seen sporadically from 11th century, becoming regular at the end of the 16th century.
However, suggests that onbin changes must have been active well before these dates, arguing that they precede the intervocalic merger of and (dated at the latest to the end of the 10th century) and most likely began in the early 9th century or even the late 8th century.
Adjective endings
Two suffixes used in the inflection of adjectives underwent onbin changes. The Old Japanese adnominal ending developed by onbin into the Late Middle Japanese and Modern Japanese nonpast ending , as in , the nonpast form of the adjective stem . The adjectival infinitive ending developed an onbin variant : however, remains the normal form of this ending in Standard Japanese. The use of (which fuses with the preceding vowel) as an adjectival infinitive ending is a characteristic of the language spoken in the Kansai (including Kyoto) and Kyushu regions. Using the adjective again as an example, the Kansai dialect form corresponds to the Standard Japanese infinitive . The pronunciation of the adjectival infinitive ending as in Kyoto vs. in the Kanto region is mentioned as a dialectal difference in Rodrigues' Arte da Lingoa de Iapam. The variant ending shows some limited use in Standard Japanese as part of the rarely used "super-polite" construction (which occurs when the adjective is followed by the copula ) and in a few isolated, fixed expressions: its use in these contexts can be attributed to borrowing from the Kyoto dialect.
Phonetic development