One thin, very high sound that is too sharp for the ear. It does not have to be loud. It gets through everything else in the room and you cannot put it aside, and after a few seconds you want it to stop. Every other use of shrill borrows that feeling — the bird, the kettle, the phone, and then the voice, and then the argument that lands on people the same way.
From the word’s history
Late Middle English schrille, from Old English sċill (sounding, sonorous); the source notes it is probably imitative, that is, the word was made to sound like the noise it names.
來源說 shrill 出自中古英語 schrille，更早是古英語 sċill（響亮的），而且很可能一開始就是在模仿聲音本身。這條線索正好對上它的核心畫面：這個字的重點從頭到尾都在「那個聲音聽起來怎麼樣」，不在別的地方。
Wiktionary etymology_text supplied in the evidence packet (kaikki:3f6f69a190036ae4:891008688:22365)
登入就可以看每一支怎麼連回核心畫面。