What could cause me to hear my heart beat in one of my ears every couple of days? rarely eyes get watery when hearing heart beat.

Ears: We hear by 2 mechanisms: external sounds via air conduction and internal sounds by bone conduction. Normal anatomy: your carotid artery passes through the bone that makes up your inner ear. Bottom line: you likely have serous otitis media or an intermittently congested eustachian tube. When your external hearing is diminished, you hear the softer internal blood flow. This is not dangerous.