完形填空(阅读以下材料 回答第51——65题)Singing Alarms Could Save

完形填空(阅读以下材料，回答第51——65题)

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 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

Cumbria.______(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 is 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.

51._________

A. without

B. with

C. having

D. selling