Can you hear me now?
Although Beijing’s Imperial Vault of Heaven astounds tourists and worshippers, it is the temple’s outer wall that truly amazes those who discover it. Dubbed “Echo Wall,” this temple’s surrounding circle utilizes the theory of sound waves, enabling long-distance conversation to travel the length of the wall. Words whispered from the landmark’s east base reverberate along the wall allowing an individual at the west side to hear the spoken words. At Echo Wall, speech can travel, unaided by modern technology, for more than 100 feet—now, that is true wireless communication! Can you hear me now?