I think I saw something similar - at the Toronto Science Museum maybe 24 years ago (!) It was a display where a device with a speaker made a pulse tone which *sounded* like each tone was higher than the last. There wasn't an explanatory note ! (It was meant to be a brain teaser). The only thing i caould think of was that it was an "aural illusion". I think each tone drops in pitch slightly towards the end each pulse. That way, the next tone, starting fresh, sounds higher than the last. In fact, its the same pitch each time, but each pulse tails off slightly - leading to the "illusion".