It's a classic situation ... a family is watching TV, but in order for the grandparents to be able to hear it, the volume is turned up too loud for everyone else's liking. A PhD student from the University of Southampton, however, might have a solution. Marcos Simón has developed a speaker system that projects high-volume audio to just one spot in the room.
Simón's system is designed to compensate for the hearing loss typically experienced by 70 year-old individuals.
It consists of an array of eight acoustical radiators (loudspeakers, essentially) arranged in a line, which work together to focus a "hot spot" of sound to a specific area. In tests of the array, it boosted partially-deaf listeners' ability to make out played-back human speech by about 30 percent. Non-deaf test subjects who were seated nearby but not in the hot spot, meanwhile, heard the same speech at a comfortable volume.
Simón notes that while other "line arrays" have been studied previously, they've required a second set of acoustic radiators in the rear, to cancel out stray sound waves that were emitted from the back of the primary set. This would make the technology fairly impractical to commercialize.

Source: University of Southampton