Singing Alarms Could Save the Blind If you cannot see, you may not be able to find your way out of a burning building-and that could be fatal. A company in Leeds could(51)all that with directional (定向的) sound alarms capable of guiding y0uto the exit. Sound Alert, a company run(52)the University of Leeds, Is installing the alarms in a residential home for(53)people In Sommerset and a resource centre for the blind in Cumbria. The alarms produce a(54)range of frequencies that enable the brain to(55)where the sound is coming from. Deborah Withington of Sound Alert says that the alarms' use most of the frequencies that can be(56)by humans. 'It is a burst of white noise that people say sounds like static (静电噪音) on the radio,' she says. 'Its life-saving potential is(57).' She conducted an experiment in which people were filmed by thermal-imaging (热效应成像) cameras trying to find their(58)out of a large smoke-filled room. It(59)them nearly four minutes to find the door without a sound alarm,(60)only 15 seconds with one. Withington studies how the brain(61)sounds at the university. She says that the(62)of a wide band of frequencies can be pinpointed (精确地确定) more easily than the source of a narrow band. Alarms(63)on the same concept have already been installed on emergency vehicles. The alarms will also include rising or falling frequencies to(64)whether people should go up or down stairs. They were(65)with the aid of a large grant from British Nuclear Fuels.