over the years I have figured out the 'singing' in my ears is from me actually hearing the blood flow in my ears. I can hear the 'pulse' and can hold my fingers over my pulse points in my wrist or neck and the pulse is timed to my blood pulse. When I exert myself, I hear the singing pick up and when resting it diminishes. Depending on what I am taking or not taking for medication is what 'pitch' it is, too. I am sitting here typing away, hearing my blood (in their capillaries and arteries, of course) in my ears.
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Alis volat propriis
State Motto of Oregon