Japanese phonology

Japanese phonology is the system of sounds used in the pronunciation of the Japanese language. It helps us understand how words are spoken and why they sound the way they do in Japanese. The standard way of speaking Japanese is based on the Tokyo dialect, which many people use as a model.

There are different ideas about exactly how many individual sounds, called phonemes, are in Japanese. Most people agree there are at least 12 distinct consonants, though some say there are up to 21, and 5 distinct vowels: /a, e, i, o, u/. In Japanese, the length of vowels and consonants can change the meaning of a word, and this length is measured in units called mora. Only certain groups of consonants are allowed to come together in words.

Japanese also uses a special way of changing pitch to show meaning. By raising or lowering the voice on certain syllables, you can tell different words apart, like /haꜜsiɡa/ (箸が, 'chopsticks') and /hasiꜜɡa/ (橋が, 'bridge'). The sounds in Japanese have been shaped by many influences, including words from Chinese and borrowed words from other languages, which add variety to the sounds we hear.

Lexical strata

Japanese sounds can behave differently depending on where the words come from. This is why experts often talk about different "layers" or groups of words in the language.

Yamato

Main article: Wago

These are the original, native Japanese words. They follow certain sound rules that other word groups do not.

Mimetic

Main article: Japanese sound symbolism

Japanese has special words that imitate sounds or feelings. These words also come from the native language but have their own unique sound patterns.

Sino-Japanese

Main article: Sino-Japanese vocabulary

These words came from Chinese over many centuries, starting from around the 6th century AD. They make up a big part of Japanese vocabulary, both in writing and speaking. Most of these words are made from smaller sound units called morphemes, which usually have one or two beats, known as moras. These words are often written using Chinese characters called kanji.

Foreign

Main article: Loanwords in Japanese

These are words borrowed from other languages, especially Western languages, mostly after the 16th century. Many entered Japanese in the 20th century. These words often have sound combinations that are new to Japanese, leading to new ways of writing them.

Consonants

Different linguists analyze the Japanese inventory of consonant sounds in significantly different ways. Some recognize only 12 underlying consonants, while others recognize 16 or even 21, depending on how they interpret certain sounds. In some analyses, glides or semivowels are not considered consonant phonemes.

Phonetic notes

Details of articulation

• Sounds like t, d, n can be pronounced in slightly different ways, such as with the tip of the tongue against the teeth or the roof of the mouth.
• Sounds like ts, s, dz~z are made with the tip of the tongue against the roof of the mouth.
• Sounds like tɕ, ɕ, dʑ~ʑ are made with the tongue against the roof of the mouth and the palate.
• The sound w is traditionally described as a sound made in the back of the mouth, but recent studies suggest it may be made more forward with the lips rounded.
• The sound h changes depending on what sound follows it and can be pronounced in different ways.
• The sound r can vary greatly depending on its position in a word and dialect, and can be pronounced as a tap, a lateral, or even a trill.

Voice onset time

At the start of a word, the voiceless stops p, t, k are slightly aspirated — less so than in English, but more than in Spanish. In the middle of words, these sounds seem to be unaspirated on average.

A study found that after a pause, word-initial b, d, ɡ may be pronounced with little or no aspiration, while p, t, k are more aspirated. Vowels after p, t, k at the start of words often start with a higher pitch compared to vowels after b, d, ɡ, even when the latter are not fully voiced.

Lenition

The phonemes b, d, ɡ can have weakened pronunciations that sound like voiced fricatives, especially between vowels. These weakened pronunciations can occur after a vowel in the middle of a word, or when a word starting with b, d, ɡ follows a vowel-final word with no pause.

Moraic consonants

Certain consonant sounds are called "moraic" because they count for a mora, a unit of timing or prosodic length. The phonemic analysis of moraic consonants is disputed. One approach analyzes moraic consonants as special "mora phonemes," while a competing approach treats them as the syllable-final realizations of other consonant phonemes.

Moraic nasal

The moraic nasal can be interpreted as a syllable-final nasal consonant. It is found only after a vowel and can be followed by a consonant, a vowel, or the end of a word. Its pronunciation varies depending on the sound that follows it.

Moraic obstruent

There is a contrast between short (or singleton) and long (or geminate) consonant sounds. Geminate consonants have greater phonetic duration compared to singleton consonants. A geminate can be analyzed phonologically as a syllable-final consonant followed by a syllable-initial consonant.

Voiced affricate vs. fricative

The distinction between certain voiced fricatives and voiced affricates is neutralized in Standard Japanese. In accents with the merger, the variable sound can be transcribed phonemically as one sound, though some analyze it as another. The likelihood of the affricate realization was increased in certain phonetic conditions.

Voiceless coronal affricate

In core vocabulary, a certain sound can be analyzed as an allophone of t before u. In loanwords, however, this sound can occur before other vowels.

Palatalized consonants

Most consonants possess palatalized counterparts. Pairs of palatalized and non-palatalized consonants contrast before the back vowels a, o, u, but are in complementary distribution before the front vowels.

Alveolo-palatal sibilants

The alveolo-palatal sibilants function, at least historically, as the palatalized counterparts of certain coronal obstruents. Original ti came to be pronounced as a certain sound, and original si came to be pronounced as another, among others.

Voiceless bilabial fricative

In core vocabulary, the voiceless bilabial fricative occurs only before u. In this context, it can be analyzed as an allophone of h. In loanwords, it can occur before other vowels or before j.

Voiced bilabial fricative

Spellings with the kana vu have been used in narrow transcriptions to render a voiced labiodental fricative in other languages. The actual pronunciation of a foreign "v sound" is normally not distinguished from a Japanese b.

Velar nasal onset

For some speakers, the velar nasal can occur as an onset in place of the voiced velar plosive in certain conditions. Onset, called bidakuon, is generally restricted to word-internal position, where it may occur either after a vowel or after a moraic nasal. It is debated whether onset constitutes a separate phoneme or an allophone of g.

Distribution of [ŋ] vs. [ɡ]

At the start of an independent word, all speakers use g in almost all circumstances. However, postpositional particles, such as the subject marker ga, are pronounced with ŋ by consistent nasal speakers. In the middle of a native morpheme, consistent nasal speakers always use ŋ.

Sociolinguistics of [ŋ]

The frequency of onset ŋ in Tokyo Japanese speech was falling as of 2008, and seems to have already been on the decline in 1940. Pronunciations with ŋ are generally less frequent for younger speakers, and even though the use of ŋ was traditionally prescribed as a feature of standard Japanese, pronunciations with g seem in practice to have acquired a more prestigious status. The frequency of ŋ also varies by region.

Vowels

All Japanese vowels can be either short or long. Long vowels sound about 2.5 to 3 times longer than short vowels. In everyday speech, two identical short vowels next to each other often sound like one long vowel. But in careful or formal speech, they might sound a little different.

When two identical vowels are next to each other because of word boundaries, there can sometimes be a small pause or a slight change in sound between them. This happens, for example, in words like sato-oya (里親) but not in satō-ya (砂糖屋).

In fast speech, two identical short vowels next to each other often blend into one long vowel. This can happen between words or parts of words, like in kai-in (会員) or Tōkyō ni iku (東京に行く).

Long vowels can only be stressed on their first part, while a pair of identical short vowels can be stressed on either part. There are different ways to explain the difference between long vowels and pairs of short vowels in Japanese sound patterns.

Prosody

Japanese words are often studied as being made up of special units called moras. Unlike syllables in English, each mora takes about the same amount of time to say. A mora can be a simple vowel (V) or a consonant plus a vowel (CV). There are also special moras like /N/ and /Q/.

Japanese is sometimes called a mora-timed language because each mora usually takes the same time. However, this isn’t always strict—some sounds can be a bit shorter. Pitch also plays a role in Japanese sounds, but it doesn’t usually change how long a mora is.

Japanese uses a system where words can have different pitches to change their meaning. A special mark (ꜜ) shows where the pitch drops in a word. The rest of the word follows predictable pitch patterns. This helps tell words apart, like “edge” and “bridge,” which sound the same alone but different when more words are added.

Different areas in Japan have their own ways of using pitch, but the Tokyo dialect is often used as a standard example.

Phonotactics

Japanese phonotactics refer to the patterns of sounds used in the pronunciation of Japanese words. The language has specific rules about how sounds can combine, especially in the structure of syllables and moras (units of sound).

Japanese syllables often begin with a consonant followed by a vowel, or just a vowel. Some syllables can start with a special glide sound. The language also uses moraic consonants, which act like extra sounds attached to syllables.

Foreign words are adapted to fit Japanese sound patterns, sometimes by adding extra vowels to make pronunciation easier. These patterns help shape how Japanese words are spoken and understood.

Morphophonology

Japanese morphology is generally agglutinative rather than fusional. Nevertheless, Japanese exhibits a number of morphophonological processes that can change the shape of morphemes when they are combined in compounds, derived words, or inflected forms of verbs or adjectives. Various forms of sandhi exist; the Japanese term for sandhi generally is ren'on (連音).

Rendaku

Main article: Rendaku

In Japanese, sandhi is prominently exhibited in rendaku – consonant mutation of the initial consonant of a morpheme from unvoiced to voiced in some contexts when it occurs in the middle of a word. This phonetic difference is marked in the kana spelling of a word via the addition of dakuten, as in ka, ga (か／が). In cases where this combines with the yotsugana mergers, notably ji (じ／ぢ) and zu (ず／づ) in standard Japanese, the resulting spelling is morphophonemic rather than purely phonemic.

Yamato gemination or prenasalization

Certain processes, such as onbin sound changes, have acted to produce voiceless geminates in Yamato words (often across morpheme boundaries, but sometimes even within a morpheme). Gemination can arise as the result of emphasis, compounding, or verb conjugation. In this context, sequences of a moraic nasal /N/ and a voiced consonant are found in place of voiced geminate obstruents, which do not occur in native Standard Japanese words (other than marginally as emphatically lengthened variants of single voiced obstruents).

For example, adverbs built from a mimetic root and the suffix -ri may display root-internal gemination, as in nikkori (alongside nikori) from niko 'smiling'. Adverbs derived from roots with voiced medial consonants exhibit forms with a moraic nasal in place of gemination, such as shonbori from shobo 'lonely', unzari from uza 'bored, disappointed', bon'yari from boya 'vague', and funwari from fuwa 'light' (/r/ does not undergo either gemination or /N/-insertion in this context). Likewise, a moraic consonant often occurs between the emphatic prefix /ma/ and a following consonant: its allomorphs /maQ/ and /maN/ are in complementary distribution, with /maQ/ used before voiceless consonants and /maN/ used elsewhere.

Another example where either a voiceless geminate or /N/ is formed depending on the voicing of the following consonant is the derivation of reduced, i.e. contracted, compound verbs. Japanese has a type of compound verb formed by placing the stem of one verb before another. If the first verb has a stem that ends in a consonant, the vowel /i/ is usually placed between the first and second verb stem. But in some compounds, this vowel can be omitted, resulting in the final consonant of the first verb stem being placed directly before the initial consonant of the second verb stem. When this happens, the first consonant assimilates to the second, producing a voiceless geminate if the second is voiceless, and a sequence starting with /N/ if the second is a voiced obstruent or nasal (e.g. hik- 'pull' + tate- 'stand' > hikitateruhittateru 'support', tsuk- 'stab' + das- 'put out' > tsukidasutsundasu 'thrust out').

In verb conjugation, the voiceless geminate /Qt/ is produced when a verb root that underlyingly ends in /r/, /t/, or /w/ is followed by a suffix starting with /t/ (namely, -te, -ta, -tari, -tara, -tatte), whereas /Nd/ is produced when a verb root that underlyingly ends in /m/, /n/, or /b/ is followed by a suffix starting with /t/. (At the end of a verb stem, /w/ descends from original *p; some generative analyses interpret this as the synchronic underlying form of the consonant.)

Sino-Japanese gemination

When the second mora of a Sino-Japanese morpheme is つ, tsu, く, ku, ち, chi or き, ki and it is followed by a voiceless consonant, this mora is sometimes replaced by the sokuon っ (whose spelling as a small つ is based on the frequent alternation of these sounds in this context), forming a geminate consonant:

• 一 (いつ itsu) + 緒 (しょ sho) = 一緒 (いっしょ, issho)
• 学 (がく gaku) + 校 (こう kō) = 学校 (がっこう, gakkō)

Sino-Japanese morphemes ending in these moras remain unchanged when followed by a voiced consonant, and are usually unchanged when followed by a vowel (but see renjō for exceptional examples of geminate formation before a vowel).

• 学 (がく, gaku) + 外 (がい, -gai) = 学外, gakugai, 'outside of school campus'
• 別 (べつ, betsu) + 宴 (えん, en) = 別宴, betsuen, 'farewell dinner'
• 学 (がく, gaku) + 位 (い, i) = 学位, gakui, 'academic degree'

Gemination can also affect Sino-Japanese morphemes that historically ended in ふ, fu and that now end in long vowels:

• 法 (hafu はふ > hō ほう) + 被 (hi ひ) = 法被 (happi はっぴ), instead of hōhi ほうひ
• 合 (kafu かふ > gō ごう) + 戦 (sen せん) = 合戦 (kassen), instead of gōsen
• 入 (nifu > nyū) + 声 (shō) = 入声 (nisshō), instead of nyūshō
• 十 (jifu > jū) + 戒 (kai) = 十戒 (jikkai) instead of jūkai

Most morphemes exhibiting this change derive from Middle Chinese morphemes ending in /t̚/, /k̚/ or /p̚/, which developed a prop vowel after them when pronounced in isolation (e.g., 日 MC */nit̚/ > Japanese /niti/ [ɲitɕi]) but were assimilated to the following consonant in compounds (e.g. 日本 MC */nit̚.pu̯ən/ > Japanese /niQ.poN/ [ɲip̚.poɴ]).

Gemination occurs regularly in words consisting of two Sino-Japanese morphemes, but tends not to occur across the major boundary of a complex compound (where one of the components is formed of more than one Sino-Japanese morpheme). However, there are some cases of gemination in this context.

The formation of a geminate also depends on the identity of the first and second consonant:

Renjō

Further information: and Late Middle Japanese § Medial gemination

Sandhi also occurs much less often in renjō (連声), where, most commonly, a terminal /N/ or /Q/ on one morpheme results in /n/ (or /m/ when derived from historical m) or /t̚/ respectively being added to the start of a following morpheme beginning with a vowel or semivowel, as in ten + ō → tennō (天皇: てん + おう → てんのう). Examples:

First syllable ending with /N/

• 銀杏 (ginnan): ぎん (gin) + あん (an) → ぎんなん (ginnan)
• 観音 (kannon): くゎん (kwan) + おむ (om) → くゎんのむ (kwannom) → かんのん (kannon)
• 天皇 (tennō): てん (ten) + わう (wau) → てんなう (tennau) → てんのう (tennō)

First syllable ending with /N/ from original /m/

• 三位 (sanmi): さむ (sam) + ゐ (wi) → さむみ (sammi) → さんみ (sanmi)
• 陰陽 (onmyō): おむ (om) + やう (yau) → おむみゃう (ommyau) → おんみょう (onmyō)

First syllable ending with /Q/

• 雪隠 (setchin): せつ (setsu) + いん (in) → せっちん (setchin)
• 屈惑 (kuttaku): くつ (kutsu) + わく (waku) → くったく (kuttaku)

Vowel fusion

1. usually not reflected in spelling

During Late Middle Japanese, multiple vowel changes took place. Notably, the vowel /u/ tended to fuse with another vowel that preceded it, creating a long vowel. These vowel fusions are not reflected in historical kana usage, particularly that for classical Japanese.

• ou → oː
• au → ɔː → oː
• jeu → joː
• iu → juː

These historical changes are still germane to modern grammatical analysis and education. For example, the "volitional/tentative" auxiliary u (う) (historically mu (む)) notably fused with the last vowel of a mizenkei (未然形) (see Japanese conjugation#Verb bases):

• godan (五段):
  • kaka + mu → kakamu → kakau → kakɔː → kakoː（書かむ → 書かう → 書こう）
  • ʷaɾapa + mu → ʷaɾapamu → ʷaɾaɸamu → ʷaɾaʷau → ʷaɾaʷɔː → ʷaɾaʷoː → ʷaɾaoː（笑はむ → 笑わう → 笑おう）
• ichidan (一段):
  • je + mu → jemu → jeu → joː → ejoː（得（え）む → 得（え）う → 得（よ）う → 得（え）よう）
  • mi + mu → mimu → miu → mjuː → mijoː（見（み）む → 見（み）う → 見（みゅ）う → 見（み）よう）
• sa-hen (サ変):
  • sje + mu → sjemu → sjeu → sjoː → sijoː（せむ → せう → しょう → しよう）
• The ra-hen (ラ変) verb ari/aru (あり・ある) and its derivations:
  • aɾa + mu → aɾamu → aɾau → aɾɔː → aɾoː（あらむ → あらう → あろう）
  • naɾa + mu → naɾamu → naɾau → naɾɔː → naɾoː（ならむ → ならう → なろう）
  • daɾa + mu → daɾamu → daɾau → daɾɔː → daɾoː（だらむ → だらう → だろう）
  • taɾa + mu → taɾamu → taɾau → taɾɔː → taɾoː（たらむ → たらう → たろう）
  • nakaɾa + mu → nakaɾamu → nakaɾau → nakaɾɔː → nakaɾoː（なからむ → なからう → なかろう）
• Other jodōshi (助動詞):
  • desje + mu → desjemu → desjeu → desjoː（でせむ → でせう → でしょう）
  • masje + mu → masjemu → masjeu → masjoː（ませむ → ませう → ましょう）

Thus, while the mizenkei is listed in inflection tables, a combination of it and the auxiliary u, dubbed "volitional form" (意志形, ishikei) or "tentative form" (推量形, suiryōkei), must still be learnt separately. Furthermore, results of the above fusions caused some mizenkei to disappear entirely. Dictionaries and grammar guides no longer list たら, だら, でせ and なから as, respectively, the mizenkei of た, だ, です and ない. Instead, たろ, だろ, でしょ and なかろ are perfunctorily used. This perfunctory listing may also extend to godan verbs as well, for example 書く may have "two" mizenkei, 書か and 書こ, so that it has enough vowels to justify the term godan (see Japanese godan and ichidan verbs#Godan vs yodan).

In contemporary Japanese, sequences such as /ae, ai, oi/ can fuse into [eː ~ ɛː] in masculine speech. This particular fusion is associated with non-Tokyo dialects, as well as Tokyo's male and/or delinquent sociolects. Some examples include nai → nē (ない → ねえ; negative auxiliary adjective), tai → tē (たい → てえ; desiderative auxiliary adjective), semai → semē (狭い → 狭え; 'narrow'), sugoi → sugē (凄い → 凄え; 'terrible/very bad; terrific/very good') (as well as most adjectives ending in ai and oi), omae → omē (お前; 'you'), atari mae → atari mē (当たり前; 'of course'), etc. This fusion does not straddle word boundaries, hence does not occur in ore ga iku (俺が行く; 'I'll go') or ore mo iku (俺も行く; 'I'll go, too'). It is also lexically restrictive and does not occur in such words as koitsu (こいつ; 'this guy'), kiiroi (黄色い; 'yellow'), saigo (最後; 'last'), kimae (気前; 'generosity'), etc. The glides [j, β̞] are said to not occur before /e/ in contemporary native Japanese (excluding recent loanwords), yet they may still be heard in hayai → haē (早い → 早え; [hɑ̈jɑ̈́i → hɑ̈jé̞ː], 'quick') and kowai → koē (怖い → 怖え; [ko̞β̞ɑ̈́i → ko̞β̞é̞ː], 'scary'). At least some speakers are cognizant enough of this that they can spell 怖え in kana as kowē (コウェー). yoi (良い; 'good') has some variants, ii ~ ī, ei and ē. The same dialects and sociolects also have ui become ī, as in warui → warī (悪い; 'bad'). The sequences /oi/ and /ui/ undergo fusion only in adjective forms.

Onbin

Main article: Onbin

Further information: Japanese grammar § Euphonic changes (音便, onbin); and Onbin in verb conjugations

Another prominent feature is onbin (音便; euphonic sound change). This refers to various historical sound changes that can be loosely described as showing reduction, lenition or coalescence. Alternations resulting from onbin continue to be seen in some areas of Japanese morphology, such as the conjugation of certain verb forms or the form of certain compound verbs.

In some cases, onbin changes occurred within a morpheme, as in hōki (箒 (ほうき); broom), which underwent two sound changes from earlier hahaki (ははき) → hauki (はうき) (onbin) → houki (ほうき) (historical vowel change) → hōki (ほうき) (long vowel, sound change not reflected in kana spelling).

One type of onbin caused certain onset consonants to be deleted, mainly before /i/ or /u/, which created vowel sequences, or long vowels by coalescence of /u/ with the preceding vowel.

Another type of onbin resulted in the development of moraic consonants /Q/ or /N/ in certain circumstances in native Japanese words.

Types

Types of onbin are named after their resulting mora. If the resulting mora is /i/, the onbin is called i-onbin (イ音便); if /u/, u-onbin (ウ音便); if /Q/ (促音, sokuon), sokuonbin (促音便); and if /N/ (撥音, hatsuon), hatsuonbin (撥音便).

Historically, sokuonbin was triggered in verb conjugation when any of the morae /ti, ɾi, si, pi/ in a ren'yōkei (連体形) (see Japanese conjugation#Verb bases) was followed by the consonant /t/ (for example in the auxiliary ta (た) or the particle te (て)). In such an environment, the high vowel /i/ was reduced, and the remaining consonant eventually assimilated with /t/:

• toɾi + te → toɾite → toɾte → totte（取って）
• kapi + te → kapite → kaɸite → kaʷite → kaʷte → katte（買って）
• ipi + te → ipite → iɸite → iʷite → iʷte → itte（言って）

Grammatical sokuonbin is found predominantly in eastern dialects (including the standard Tokyo dialect taught to foreigners), while western ones (including the Kansai dialect) favor u-onbin triggered by the historical mora /pi/:

• kapi + te → kapite → kaɸite → kaʷite → kaute → kɔːte → koːte（買うて）
• ipi + te → ipite → iɸite → iʷite → iute → juːte（言うて）

On the other hand, hatsuonbin was triggered when any of the morae /mi, bi, ni/ in a ren'yōkei was followed by the consonant /t/. Similar vowel reduction and consonant assimilation occurred:

• pumi + te → pumite → pumute → punde → ɸunde（踏んで）
• jobi + te → jobite → jomute → jonde（呼んで）
• sini + te → sinite → sinde（死んで）

In general, onbin can occur in the following historical environments:

• i-onbin:
  • When a ren'yōkei with the mora /ki/, /ɡi/, or rarely /si/, was followed by /t/:
    • kaki + te → kakite → kaite（書いて）
    • ojoɡi + te → ojoɡite → ojoide（泳いで）
    • sasi + te → sasite → saite（指いて）
  • When the ren'yōkei of the verb yuku (行く; "to go") was followed by /t/:
    • juki + te → jukite → juite（行いて）
  • When the mora /ɾi/ in ren'yōkei and meireikei (命令形) lost the consonant /ɾ/ in certain honorific verbs:
    • ossjaɾi → ossjai（仰い）
  • When the historical rentaikei (連体形) of an adjective lost the consonant /k/. This particular type of i-onbin resulted in what is now known to foreign learners as "-i adjectives":
    • atuki → atui（熱い）
    • utukusiki → utukusii（美しい）
  • In certain verbs:
    • tate + maturu → tatematuru → taimaturu（奉（たいまつ）る）
  • In certain nouns:
    • kisaki → kisai（后（きさい））
• u-onbin:
  • When a ren'yōkei with the mora /pi/, /bi/ or /mi/ was followed by /t/:
    • omopi + te → omopite → omoute → omoːte（思うて）
    • jobi + te → jobite → joude → joːde（呼うで）
    • jami + te → yamite → jaude → jɔːde → joːde（病うで）
    • tanomi + taru → tanomitaru → tanoudaru → tanoːdaru（頼うだる）
  • When the ren'yōkei of the verbs tou (問う; "to ask") and kou (請う; "to request") were followed by /t/, even in eastern dialects:
    • topi + te → topite → toute → toːte（問うて）
    • kopi + te → kopite → koute → koːte（請うて）
  • When the mizenkei (未然形) of an adjective lost the consonant /k/:
    • joku → jou → joː（良う）
    • aɾiɡataku → aɾiɡatau → aɾiɡatɔː → aɾiɡatoː（有り難う）
    • pajaku → pajaku → ɸajau → hajɔː → hajoː（早う）
    • utukusiku → utukusiu → utukusjuː（美しゅう）
  • In certain nouns:
    • ʷo + pito → ʷopito → ʷouto → oːto（夫（おうと））
    • opi + te → opite → opute → oute → oːte（追手（おうて））
    • oto + pito → otopito → otouto → otoːto（弟（おとうと））and in many other compounds of Old Japanese pi₁to₂
    • kaɡapuɾi → kaubuɾi → kɔːbuɾi → koːbuɾi（冠（こうぶり））
  • In the verb yuu (言う)
    • ipu → iɸu → iu → juː（言う）
• Sokuonbin:
  • When a ren'yōkei with the mora /ti/, /ɾi/ or /pi/ was followed by /t/:
    • kati + te → katite → katte（勝って）
    • aɾi + te → aɾite → atte（有って）
    • kupi + te → kupite → kutte（食って）
  • When the ren'yōkei of the verb iku (行く; "to go") was followed by /t/:
    • iki + te → ikite → iite → itte（行って）
  • In certain nouns:
    • ʷo + pito → ʷopito → ʷotto → otto（夫（おっと））
    • opi + te → opite → otte（追っ手）
    • sau + soku → sausoku → sassoku（早速（さっそく））
    • japaɾi → jappaɾi（矢っ張り）
    • ma + siɾo → masiɾo → massiɾo（真っ白）
• Hatsuonbin:
  • When a ren'yōkei with the mora /mi/, /bi/ or /ni/ was followed by /t/:
    • jomi + te → jomite → jonde（読んで）
    • tobi + te → tobite → tonde（飛んで）
    • sini + te → sinite → sinde（死んで）
  • In certain expressions formed with the particles ni (に) and no (の):
    • sakaɾi + ni → sakaɾini → sakanni（盛んに）
    • nokoɾi + no + juki → nokoɾinojuki → nokonnojuki（残んの雪）
  • In certain nouns:
    • kami + na + tuki → kaminaduki → kannaduki → kannazuki（神無月（かんなづき））
    • kami + sasi → kamisasi → kanzasi（簪（かんざし））
    • ma + naka → manaka → mannaka（真ん中）

Polite adjective forms

Further information: Japanese grammar § Polite forms of adjectives

The polite adjective forms (used before the polite copula gozaru (ござる; be) and verb zonjiru (存じる; think, know)) exhibit a one-step or two-step sound change. Firstly, these use the continuative form, -ku (-く), which exhibits onbin, dropping the k as -ku (-く) → -u (-う). Secondly, the vowel may combine with the preceding vowel, according to historical sound changes; if the resulting new sound is palatalized, meaning yu, yo (ゆ、よ), this combines with the preceding consonant, yielding a palatalized syllable.

This is most prominent in certain everyday terms that derive from an i-adjective ending in -ai changing to -ō (-ou), which is because these terms are abbreviations of polite phrases ending in gozaimasu, sometimes with a polite o- prefix. The terms are also used in their full form, with notable examples being:

• arigatō (有り難う、ありがとう; Thank you), from arigatai (有り難い、ありがたい; (I am) grateful).
• ohayō (お早う、おはよう; Good morning), from hayai (早い、はやい; (It is) early).
• omedetō (お目出度う、おめでとう; Congratulations), from medetai (目出度い、めでたい; (It is) auspicious).

Other forms like this are found in polite speech, such as oishiku (美味しく) → oishū (美味しゅう) and ōkiku (大きく) → ōkyū (大きゅう).

Earlier domestic phonology

During the late Edo period and Meiji era, people studied Japanese sounds using a method called fanqie. This method came from studying sounds in Middle Chinese. It breaks down a sound into two parts: the first part is like the beginning of the sound, and the second part is like the ending.

For example, the Japanese word for "east" [tuŋ] was broken down using three Chinese characters. One character showed the beginning sound, another showed the ending sound, and a third was the sound being studied. In Japanese, these characters were called the "father character" (父字, chichiji), the "mother character" (母字, hahaji), and the "child character" (子字, koji).

People also used ideas from Chinese to describe Japanese sounds, like "clear sound" for sounds without special marks, and "muddy sound" for sounds with a special mark called dakuten. Other ideas included "rushed sound" for short sounds and "open sound" and "closed sound" for different kinds of vowel sounds.