单选题
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 change all that (51) directional sound alarms capable of guiding you to the exit.
Sound Alert, a company (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 Columbia. (54) produce a wide range of frequencies that enable the brain to determine where the (55) is coming from.
Deborah Withington of Sound Alert says that the alarms use most of the frequencies that can be (56) by humans. "It's a burst of white noise (57) people say sounds like static on the radio," she says. "Its life-saving potential is great."
She conducted an experiment in which people were filmed by thermal-imaging cameras trying to find their way out of a large (58) room. It (59) them nearly four minutes to find the door (60) a sound alarm, but 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 more easily than the source of a narrow band. Alarms (63) the same concept have already been installed on emergency vehicles.
The alarms will also include rising or falling frequencies to indicate whether people should go up (64) down stairs. They were (65) with the aid of a large grant from British Nuclear Fuels.