Yesterday during the process of changing lights in the MSR, it was discovered that an end cap had been dislodged from a section of duct work. The end cap was replaced and secured with tek screws. This in turn redirected a large portion of the air flow to the control room which increased the noise factor. I have adjusted the flow to the control room to a more pleasant audible level. The air flow was 19000 cfm and is now set at 12000 cfm.