Sough – to make a moaning or sighing sound.
http://www.merriam-webster.com/dictionary/sough
Used in “The Metamorphosis”, on page 20; middle of the second paragraph.
He was still occupied with this difficult movement, unable to pay attention to anything else, when he heard the chief clerk exclaim a loud “Oh!”, which sounded like soughing in the wind.
At first, I thought the word “sough” meant to bury something. The word in the sentence describes how the chief clerk says “Oh”. I pictured it to sound somewhat breathless and scared as he saw Gregor in his terrifying state.
