A hearing aid includes a housing and a hook, the housing defining a top area and a bottom area, a front end and a rear end, and contains a microphone, an amplifier, a receiver, and a battery for power supply, and the hook is attached to the housing and transmits acoustic signals from the receiver into the ear of the user. Included are: a first relay device 4a including first and second Bluetooth\xae modules {circle around } and {circle around }. In this case the solder bump is provided as a fluid layer with a contact angle of less than 90\xb0 C. 1 mg per g biomass dry weight of the sphingoid base of Formula I. The voltage generator is responsive to the logic signal and produces a voltage signal at a connector connectable to the second circuit board. A preferred method of camouflage is color differentiation, wherein the second body member is darker than the first body member.