I wonder in this case if there is any rule that turns H to P.

  • 2
    @Flaw Actually, /h/ → /p/ is actually not rendaku — see the comments on this question. I don't think we have a clear discussion of /h/ to /p/ alternation...
    – Earthliŋ
    Commented Aug 19, 2018 at 15:06
  • @Earthliŋ That's fair.
    – Flaw
    Commented Aug 19, 2018 at 15:07

2 Answers 2


In Japanese (native) and Sino-Japanese words, ん and っ make the next consonant //h// to //p//. The sound change is a grammatical demand that no longer has phonetic ground, as much as English critic vs criticize.

Long story
Once upon a time, the Japanese consonant that we today call //h// had the sound [[p]]. This sound was weakened to [[ɸ]] by at latest 10th c. (母は昔はパパだった), then to [[h]]-like sounds (except ふ) by at latest 18th c. (ハマの二つは唇の軽重). But there are two cases that these changes were met with resistance.

  1. //p// preceded by consonantal element, now converged into either ん (nasal stop) or っ (reduplication)

    歩 [[po]] → [[ho]] "step" : 一歩 [[it.po]] → [[ippo]] "one step"
    歯 [[pa]] → [[ha]] : 出歯 [[de.ba]] "bucktoothed" (rendaku) : 出っ歯 [[deʔ.pa]] → [[deppa]] "bucktoothed (slangy)"
    輩 [[pai]] → [[hai]] "fellow" : 先輩 [[sen.pai]] → [[sempai]] "senior"

  2. mimetic words; that carry sound symbolism unlike usual words

    ぴかぴか [[pikapika]] < 光 [[pikaɾi]] → [[çikaɾi]] "light"
    ぱたぱた [[patapata]] < はたく [[pataku]] → [[hatakɯ]] "pat, rap"

From today's perspective, it seems that //h// occasionally turns into //p//, but it's actually //p// is occasionally retained until today.

ヨーロッパ, the Japanese transcription of Portuguese Europa, attests two important facts at the Late Middle Japanese stage: (1) reduction of diphthongs //eu// → //joo//; (2) //p// unable to appear in the middle of word without reduplication *//-pa// → //-Qpa//.


Why? Well, it was practically for the same reason that English-speakers "stopped" pronouncing the "gh" in words such as "night", "daughter", etc. many years ago. The "gh" part was simply too difficult to keep pronouncing.

Likewise, it was and still is a little bit difficult for native Japanese-speakers to say out loud 「せんい」, so we started pronouncing it as 「せんい」.

Not that you would need to remember this big technical term if you are a beginner, but this phenomenon is called 「半濁音化{はんだくおんか}」. My own translation of that would be "P-sound-ification".

半濁音化 mostly occurs in Sino-loanwords used in Japanese. The H sound turns into the P sound when it follows, for the most part, a 「ん」 or 「っ」 (small っ).

先輩 (one's seniors): せんい ⇒ せん

審判 (umpire): しんん ⇒ しん

絶品 (object of superb quality): ぜっん ⇒ ぜっ

脱皮 (molting): だっ ⇒ だっ

The list will be almost endless as we use tens of thousands of Sino-loanwords. Unlike what some Japanese-learners mistakenly seem to believe, the vast majority of our loanwords come from Chinese and certainly not English.

  • 4
    But historically, /p/ was the original pronunciation, and the change was (eventually) to /h/, so calling it P-sound-ification seems backwards. Those phonetic contexts are just preserving the older sound.
    – user1478
    Commented Aug 20, 2018 at 10:59

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