You might consult an ENT with regard to this. It could be simply a small artery near the eardrum. It could be due to an AV malformation near the middle ear. (An AV malformation is where an artery grows into an vein directly and this causes too much pressure on the vein side. This type mlformation may be heard if it were near your middle ear)
Another possible cause would be if it were transmitted noise from a carotid occlusion. This is referred to as a carotid bruit. A whoosing sound may be heard with a stethoscope over your carotid arteries if this were the case.
Checking for carotid occlusion is a must I would say. Other tests might be considered to checke your vasculature. It is very possible that all tests could be negative and fail to reveal the casue. (This would not be a bad outcome)
I hope this information is helpful to you. If you have further questions then let me know and iw ill be happy to get back with you. if my answer has been helpful and to your satisfaction then please remember to press the "ACCEPT" button. Thank you and Best Regards,
Anthony Bray MD