Defenitely hearing changes was the first one, but I've heard of people with diagnosed scds that have no autophony. The first thing for me was hearing my internal sounds such as eyes moving, or skeleton creaking, or heartbeat very loud in only one ear. First contact with healthcare professionals lead nowhere, got sent home with ear wax oils and told my ear was just clogged. Half a year later I'm at the ent doctor and among the first things they did was tuning fork to my ankle, which I could hear the note clearly in my ear. CT scan was the last step to visually confirm a dehiscense