single-kana sound; straight sound
Linguistics term for a mora represented by a single kana without a diacritic or small kana, e.g. か, き, く, け, こ, as opposed to 拗音 (yōon) like きゃ or 促音 (sokuon) like っ.
'Ka' is a straight sound, while 'kya' is a contracted sound.
Please explain the difference between straight sounds and contracted sounds.
depalatalization
writing palatalized sounds with a single kana
Compound of 直 (choku, 'straight, direct') and 音 (on, 'sound'). The term is a technical coinage within Japanese linguistics to describe a simple, unmodified kana sound.