質問: I recently purchased a copy of One Hundred Leaves: A new annotated translation of the Hyakunin Isshu to try and improve my Japanese reading level. In addition to the English translation, each poem also includes the original Japanese and a rōmaji pronunciation guide. The second poem in the collection is by Empress Jitō (持統天皇). In the book, the Japanese text is given as (emphasis mine): > > 春過ぎて > > 夏来にけらし > > 白妙の > > 衣ほす**てふ** > > 天の香具山 > > > The corresponding rōmaji for `てふ` is given as `chou`. I understand that pronunciation can change over time, e.g. the particles `は`, `へ`, and `を`. But `てふ ⟶ ちょう` is a less obvious change. Can someone please explain why `てふ` is pronounced `ちょう`? Related info ------------ I found this page which I think is trying to tell me that `てふ` is a contracted form of `といふ`, i.e. `と言]{い}う`. Indeed, the [English version of the poem on Wikipedia translates the `てふ` as "So they say". But I still don't understand how this relates to the pronunciation being `ちょう`. I also looked for the answer on the Wikipedia page for classical Japanese language, which gives a bunch of examples of differences of pronunciation between modern and classical Japanese, but I don't understand the explanations well enough to determine if some rule or combination of rules listed on that page can explain `てふ ⟶ ちょう` (or was it `ちょう ⟶ てふ`?). Finally, the kotobank.jp entry for `ちょう〔てふ〕` mentions something about an `[音変化]{おんへんか}` and seems to indicate an intermediate step in the pronunciation change, i.e. `ちょう→ちゅう→とう`? Or maybe I am misunderstanding what the `→ちゅう→とう` on that page is trying to tell me.
回答: The best answer that I could find was this answer on Yahoo.jp 知恵袋, which goes: 「てふ」→(ハ行転呼)→「てう」 「てう」→(拗長音化)→「チョー(表記は「ちょう」)」 > > 頭語以外の「はひふへほ」を原則「わいうえお」にする > というのは「ハ行転呼」ですが、 > これが起こった上で、さらに発音が変化して > 「チョー(ちょう)」になっています。 > > > 「けふ(今日)」→「きょう」、 「きふ(急)」→「きゅう」、 なども、同じことが起きています。 ハ行転呼 拗長音