Hey Emma,
Like many folks have said, hamsters vary heavily in their different types of personalities and behaviors. My current hamster, Boo II (RIP Boo I), acclimated to my wife and I within a few days. However, Boo I was much like your hamster and it took her 3 weeks to become fully comfortable in her environment. I would say that patience is key here as it is with all things
You're doing great, however, in getting Pingado adjusted to your voice by softly talking to him! I guess I would also say, as well, that you should make sure that he's in a quiet area and that, if his cage is on the floor, that he is not being disturbed by the vibrations of your footsteps throughout the house. Furthermore, as Ria mentioned, Pingado may just be active at odd times of the night. Most hamsters tend to be crepuscular (meaning they're active at dawn/dusk). However, Boo II is active from, I've noticed, 2am-3am. If you don't happen to be a night owl such as myself, you may simply just be missing him