銼刀本身，以及磨東西的動作
這一支就是核心畫面本身：那把粗齒的工具，和拿著它工作的動作。先認得這一支，後面的聲音用法會好懂很多。
noun · B2
A metal hand tool with a very rough surface, used to wear down and shape wood, metal or other hard material.
銼刀；粗銼
核心畫面
Picture a rough metal file with rows of small raised teeth. Someone drags it along a piece of wood, stroke after stroke. Two things happen at the same time: a layer of the wood is worn away, and the room fills with a dry scratching noise. Almost every use of rasp keeps one of those two halves — the rough rubbing, or the rough sound the rubbing makes. In everyday English the sound half is the one you meet far more often, above all for a dry, worn-out voice.
可以想成一把粗粗的金屬銼刀，表面全是細小的尖齒。有人拿著它，在木頭上一下一下推過去。同一個動作會帶出兩件事：木頭被磨…更多收起
可以想成一把粗粗的金屬銼刀，表面全是細小的尖齒。有人拿著它，在木頭上一下一下推過去。同一個動作會帶出兩件事：木頭被磨掉一層，還有那個乾乾的、刮耳朵的聲音。rasp 的各種用法，幾乎都是從這兩半裡挑一半來用。日常英文最常遇到的是「聲音」那一半，特別是形容沙啞疲憊的嗓子。From the word’s history
Wiktionary traces rasp to Middle English raspen 'to scratch, scrape', borrowed from Old French rasper 'to grate, scratch', and further back to Vulgar Latin *raspāre and Frankish *hraspōn. The oldest recorded meaning is the scraping action, which is the same action the tool and the sound both come from.
根據 Wiktionary，rasp 來自中古英文 raspen（抓、刮），再往前是古法文 rasper「磨、刮」，更早可以接到通俗拉丁文 *raspāre 與法蘭克語 *hraspōn。最早記錄下來的意思就是「刮」這個動作。工具與聲音，都可以看成從這個動作長出來的兩面。
Wiktionary etymology text supplied in this evidence packet (source_ref kaikki:3f6f69a190036ae4:854799654, entry 'rasp' noun/verb, etymology 1)
Three branches
磨出來的那個刮耳聲音
同一個畫面，換聽的。銼刀磨過去的時候會發出又乾又粗的聲響，英文乾脆把那個聲音也叫 rasp。之後只要聲音有那種質地，不管來自喉嚨、門軸還是夏天的蟬，都可以用這個字。
noun · C1
A rough, scratchy sound that is unpleasant to hear, such as the sound of a dry voice, heavy breathing, or something being scraped.
刺耳粗啞的聲音
磨到人的情緒上
最後一支是把銼刀放到人身上。被磨的不再是木頭，而是耳朵、神經或脾氣。這是意思上的延伸，不是歷史上的新來源。
verb · C1
To irritate a person, their ears or their temper, in the way a rough sound or rough words seem to scrape at them.
刺激、惹毛（某人）