The present invention, generally speaking, picks up a voice or other sound signal of interest and creates a higher voice-to-background-noise ratio in the output signal so that a user enjoys higher intelligibility of the voice signal. A defect in the anulus of a disc can be repaired using a prosthesis such as a barrier. The metal layer is located on an outer surface of the large diameter portion. The pH increasing gas in the enclosure atmosphere is absorbed into water in the enclosure to increase the pH of the water. In one embodiment, the stand is configured to accept two pairs of gaming machines facing in opposing directions and includes a pair of drawers at each end and a centrally located coin compartment and electrical area. The combined measurements provided in the input parameters increases the information available to the classifier to classify materials, enabling the classifier to classify a wider range of materials.