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.