sibilant

她说话时带着明显的咝音，听起来像在窃窃私语。

Her speech had a noticeable ___sibilant quality, sounding like a whisper.

英语老师让学生们注意单词'ship'中的咝音发音。

The English teacher asked students to pay attention to the ___sibilant sound in the word 'ship'.