訓 うなが(す) ・ 音 ソク
漢越音: xúc
A person 亻 beside a foot 足, which gives both the sound soku and the image: hurrying someone's feet along. Hence sokushin, to promote or accelerate.
Stroke data: KanjiVG (CC BY-SA 3.0) — kanjivg.tagaini.net
先生は生徒に発言を促しました。 (せんせいはせいとにはつげんをうながしました)
The teacher urged the students to speak up.