"Vanya the Muscovite hates loud noise. He can "feel" heat and draws back from it." – c1964
p239 "The Cybernetic Medley"
The robot named GPTU is endowed with a faculty that is not inherent in man. It can sense radioactivity in addition to perceiving light, sound, heat and smartly circumventing obstacles. The robot initiates audible and visible alarms at a distance of a few metres from a contaminated zone. It also warns in spoken words about the hazard.
The description of the two robots may actually be of the same robot. Future research may resolve this issue.