The subwoofer is the basso profundo of speakers. Human ears can hear sounds in a range from 20 to 20,000 Hertz (cycles per second) but subwoofers concentrate on the lowest, deepest range, below about 80 Hertz.
These specialized speakers are expert conveyors of bone-vibrating movie explosions and other sounds that you feel as much as you hear them. Try one out, and you’ll never go back to ordinary sound again.