Yes, that means they know when you enter a room.
As explained in the video above, spiders have long been admired for their incredible vision and sensitivity to vibrations, but since they have no eardrums, researchers assumed they don’t hear. During a previous experiment, the Cornell team had worked out a way to implant tiny electrodes into areas of a spider’s brain that should be sound-sensitive. This is no easy feat, since a spider’s brain is about the size of a poppy seed. They used a 3-D printer to develop a frame to hold the spider still while they made a hole in its head that would quickly heal, using an ultrathin wire.
For the hearing experiment, the scientists played a sound at the same frequency as the one produced by a mud dauber wasp, insects that prey upon jumping spiders. As soon as they did, the spider froze in place and looked around for the threat, and the electrodes registered a pronounced spike in activity in the brain’s auditory area. Jumping spiders, at least, can hear.