How did Batman equip every cell phone in Gotham with the sonar technology?
Bruce Wayne indicates to Lucius Fox that he has budgeted a large amount of money to a government telecommunications project. When Lucius asks, Bruce indicates that he is “playing this one pretty close to his chest.” The audience can only assume that this was all part of a plan that Bruce had, knowing the technology would come in handy against the Joker. (Later in the film, it becomes clear why Bruce did not tell Lucius, who is upset by Batman’s spying.) It is not known exactly how Batman equipped every cell phone in Gotham with sonar technology. It is simply presented as possible, in order to advance the plot. In order to assimilate or approximate a three-dimensional space, sound waves must come in consistent stereo pairs; cell phones have a single speaker for resonating sound and a single microphone for receiving sound. Further, in order to process sound differently than they are equipped, the cell phones would need to have both their hardware and software upgraded. It is highly impro
