The purpose of this research is to study a medical device that is designed to produce lung volume reduction. This device is called the PulmonX Endobronchial Valve (EBV). It has not been approved by the Food and Drug Administration (FDA) and is considered investigational. The EBV is a one-way valve that blocks off the diseased lung section to inhaled air but lets the trapped air already inside the area escape. With placement of the EBV, the diseased part of the lung collapses which allows the healthier parts of the lung to expand. The EBV can be placed by a doctor in a diseased section of the lungs using bronchoscopy. Bronchoscopy is a way to access the lungs using a small tube with a camera on the end. With bronchoscopy, a physician can reach the airways in the lung by passing the tube through either the mouth or nose. Use of bronchoscopy for performing lung volume reduction may have fewer risks than surgery and have reduced recovery time. This study is designed to investigate the safety and effectiveness of the Pulmonx EBV for treating emphysema symptoms as compared to a standard medical therapy program alone. It is hypothesized that after placement of the EBV, lung function will be improved as compared to standard medical therapy alone.