Disclosed is a method whereby a terminal device outputs an audio signal. A spring may be coupled to the body for securing the terminal end of the trough member to the coupler, the spring including first and second spring arms extending generally in opposition to one another in a plane generally parallel to the longitudinal direction. The apparatus includes an expandable electrode that is chronically implantable in a blood vessel proximate a nerve trunk. The tab mates with the housing, and contains at least one electrical element.