Amazingly hypothyroidism is known to have an affect on hearing and ringing in the ears. From an extremely long list of symptoms that may be related to hypothyroidism, following are those that relate to hearing.
Oversensitive hearing
Noises in ears (hissing, ringing)
Deafness
Tinnitus
Internal itching of ears
Dry, scaly ear canal
Excess earwax
Vertigo
In addition, decreased hearing is listed in this link, on typical hypo symptoms.
http://endocrine-system.emedtv.com/hypothyroidism/hypothyroidism-symptoms-and-signs.html
Of course the ear ringing could be associates with other issues, but since you stated you have low thyroid, I think we should look further at that. Please post your thyroid related test results and reference ranges shown on the lab report. If you have other symptoms besides the ones you mentioned, please list those also. If you are taking thyroid medication, what type and what is the daily dose?
Ringing in the ears is not a typical sign of thyroid disease, but there can be an association between the two. Ringing in your ear can be a sign of Tinnitus or Meniere's Disease. You should see an audiologist to perform hearing and other tests to determine exactly what is causing your hearing problems. This is not something you want to leave undiagnosed and untreated for too long because you can have permanent hearing loss. Have you seen an audiologist?
If you are hypothyroid (low thyroid), this should be treated by taking thyroid hormones. Your hearing problems are separate. How is your low thyroid being treated?