1.
euphonic change: a regular sound change made for ease of pronunciation
The set of regular sound changes Japanese makes for ease of pronunciation, above all in the て and た forms of verbs (書きて → 書いて, 読みて → 読んで, 買いて → 買って), in numbers with counters (一本, 三本), and in compounds. Traditional grammar names four kinds: イ音便, 促音便 (the small っ), 撥音便 (ん), and ウ音便 (おはよう from お早く).
The reading いっぽん for 一本 is an example of the sound change that produces a small っ.
Composed of 音 (sound) + 便 (convenience): a change made for the convenience of the speaker. The term appears in grammar books and in explanations of counters and verb forms.
Types
- イ音便: き, ぎ → い (書いて, 泳いで)
- 促音便: ち, り, ひ → っ (立って, 買って; 一本)
- 撥音便: み, び, に → ん (読んで, 飛んで, 死んで)
- ウ音便: く → う (お早く → おはよう, ありがたく → ありがとう)