My ear ache.

There is an idiom in Japanese, saying that "みみがいたい", which literally means that "my ears aches"
You can use it when you are ashamed to hear something because someone is saying about your home truth something that (is/hits) close to home.

According to Kansas University's investigation, the Internet is used in the workplace for other purposes (while working/other than working).
Yes, I'm a bad teacher who enjoys (net auction sites/net auctioning) while students are solving questions.
My ear ached when I read the article.

My ear ache.

There is a an idiom in Japanese saying that "みみがいたい", which literally means that "my ears ache".
You can use it when you are ashamed to hear because someone is saying about your home truth. something someone says that hits close to home. (<- the more natural way to say this)

According to Kansas University's investigation, the Internet is used in the workplace for other purposes while than working.
Yes, I'm a bad teacher who enjoys an online net auction while my students are solving questions.
My ear ached when I read the article.  (My stomach turned when I read this article)

In English "My stomach turned" is close in meaning to "みみがいたい".

I corrected to help this sound more natural.  Nice work!