Tinnitus however, tolerate it well, and it is a significant problem in only 1–2% of people. The word tinnitus is from the Latin "tinnīre" which means "to ring". Tinnitus can be perceived in one or both ears or in the head. It is the description of a noise inside a person’s head in the absence of auditory stimulation. The noise can be described in many different ways. It is usually described as a ringing noise but, in some patients, it takes the form of a high-pitched whining, electric buzzing, hissing, humming, tinging or whistling sound or as ticking, clicking, roaring, "crickets"
Supernumerary body part considered to have lost much or all of their original function through evolution. These body parts can be classed as additional to the required functioning of the body. In human anatomy the vermiform appendix is sometimes classed as a vestigial remnant. Prosthesis is an artificial extension that replaces a body part, and cybernetics is the study of computer technology in relation to organisms which can include replacement or additional body parts. Body integrity identity disorder (BIID) is a psychiatric disorder in which a person thinks that they have one or more additional limbs than they should, despite having two arms