Sentence:  Judge Short had gone to town, and Farrar was off for a three days' cruise up the lake. I was bitterly regretting I had not gone with him when the distant notes of a coach horn reached my <WSD>ear</WSD>, and I descried a four-in-hand winding its way up the inn road from the direction of Mohair. 
Meaning of the word marked with <WSD> tags:  The external part of the organ of hearing, the auricle.