Tinnitus masker closely matched to the pitch and spectrum of the tinnitus, and as loud or somewhat louder than the perceived loudness of the tinnitus. The trigger sound is applied to the ear or ears with tinnitus and typically lasts a minute or two. Not everyone can experience RI; for those who do not, tinnitus masking is likely to be ineffective. Two qualities of a tinnitus masker need to be taken into account: how effective the masking is, and how intrusive or distracting the generated sound itself is. The masking sound may have various temporal, spectral and amplitudinal characteristics. In some cases,
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