Occlusion devices, earpiece devices and methods of forming occlusion devices are provided. An occlusion device is configured to occlude an ear canal, but other biological and non-biological conduits or chambers can be occluded using the devices and methods herein. The occlusion device includes an insertion element and at least one occluding member or element (which can be expandable) disposed on the insertion element. The occluding member is configured to receive a medium via the insertion element and is configured to expand, responsive to the medium, to contact the ear canal. Alternatively, the occluding member is made of a non-Newtonian fluid and can be enclosed by a balloon or not. Physical parameters of the occlusion device are selected to produce a predetermined sound attenuation characteristic over a frequency band. Use of a non-Newtonian fluid provides additional options or variables in customizing or designing a predetermined sound attenuation characteristic.