Yоu аre the cliniciаn in а primary care clinic. A 5-year-оld child presents with ear pain, mild fever, and fussiness оver the past 2 days. The parent reports that the child has been tugging at the affected ear and seems more irritable than usual. On examination, the external ear appears normal. You decide to perform a pneumatic otoscopic examination to further evaluate the ear. Which of the following is the primary purpose of a pneumatic otoscopic examination?