A Connecticut city has joined hundreds of others around the country that have installed new firehouse alarm systems that aim to reduce firefighters' stress when calls come in. Danbury rolled out the new system in September with softer volumes that gradually increase, warm red lighting, display screens and a computerized voice. Officials say it replaces an old system that instantly blared out loud tones that city firefighters found jarring. It also immediately alerts fire stations and the units needed after a call comes in, seconds faster than dispatchers can. Fire department leaders point to research that links gradually increasing alert volume to smaller heart-rate increases.