Tinnitus is the perception of sound in the ears or head where no external source is present. In almost all cases, tinnitus is a subjective noise, meaning that only the person who has tinnitus can hear it. It is often referred to as “ringing in the ears.” Persistent tinnitus usually indicates the presence of hearing loss. The exact cause of tinnitus is not known, but there are several likely sources, all of which are known to trigger or worsen the condition. They include noise-induced hearing loss, wax build-up in the ear canal, medicines that are toxic to the ear, ear or sinus infections, jaw misalignment, and head and neck trauma.