They put a smartphone next to a keyboard, and they had people type, and then their goal was to use the vibrations that were created by typing to measure the change in the accelerometer reading to determine what the person had been typing.
Pusieron un teléfono  inteligente junto a un teclado, y pusieron a la gente  a teclear, su meta era usar las vibraciones que  eran generadas al teclear para medir el cambio en  la lectura del acelerómetro y determinar así lo que la  persona había estado escribiendo.