If it's not clear what is going on from just looking at your ear, an ENT might be able to learn more from CT or MRI scans. When it's NOT in sync with your heartbeat, it's less common that we find explanations on the scans, however. One cause to investigate might be spasms of the middle ear muscles - two small muscles that attach to your hearing bones. These can cause "quivering" or "fluttering" type sounds that come and go randomly, not in sync with your heartbeat. This often goes away on its own, but sometimes medications or surgeries have been used to manage it.