Can't recall ever having seen that info before. Can you please post links where you found this info?
Synthroid is a stereo synthetic molecule that mimics the real thyroid molecule. Because it is similar in the type of bonds but not the true thyroid molecule (like Armour) the body is initially fooled into believing (metabolically) that it is getting a new, adequate dose of what it needs. The body, however, doesn't accommodate the stereo mimicry (being "fooled" by a look-alike molecule) very long and responds with symptoms similar to chemical poisoning (e.g. flu-like symptoms, tinnitus ringing, clicking, sluggishness, achy body, etc.) You can guess why a chemical synthetic is easier to prescribe and you can imagine how "studies" can be generated that justify its efficacy and effectiveness. The studies (for unknown reasons) overlook this 'poisoning' effect. Advice: If you're suffering ear ringing, flu-like symptoms, etc., then adjust your medication or change it.
I also have hypo and tinnitus. For me the tinnitus started a little over a year ago and is constant although more in the left ear and is sometimes really loud. I've had lots of blood work and most is normal including my fasting blood sugar level (90). I do have a slight hearing loss in the upper range (translation: old lady ear) in my left ear. The ENT says I have tinnitus because.......and I may always have it (lucky me!!!)
I have taken levo since last April (25mg at first; now 50mg) and it hasn't helped the ringing at all. However, I'm past menopause so it's not monthly cycle/hormonal for me and you might have better luck with the synthroid.
ENT did say to cut caffeine and salt which may aggravate the tinnitus. She has talked about a masker that you wear like a hearing aid to "retrain" the brain (my explaination may not be exactly right) so I don't hear the noise anymore. I think biofeedback is an interesting thought; it works for lots of other things.
Good luck, I hope you get some peace and quiet!!! ;)
Sandy