The objective of this study was to investigate differences between barrow and gilt vocalizations during a fear test. Twenty barrows and 20 gilts were tested over two consecutive weeks between 1300 and 1900 hours using a human approach test (HAT). Throughout the test, vocalizations were recorded. Gilts expressed a greater number of low calls compared to barrows; however, barrows expressed a greater number of high calls compared to gilts. Further research should be done to better understand vocalization differences between barrows and gilts during a HAT.