I recently stood at the Park St. station of the Boston T waiting for my train to get back home. Suddenly a horrible, piercing, incredibly loud sound started. I tried to move away from it only to find out that it was impossible. A “network” of boxes similar to that small red one on the top left corner of the photo. They were spaced about 5 m from each other and provided a completely homogenous sound field from which one could not escape. I moved through the platform and grabbed my iPhone —running a wonderful app named SPL which turns the iPhone into a sound level meter— and measured about 106 dB at 2-3 m. This value is not 100% accurate, but it gives you a fair idea of what was going on.
All the passengers seemed to reflect the disturbance this annoying sound caused, many tried to protect themselves by covering their ears with the hands.
I don’t know if this was some sort of malfunction, a drill or a real accident but everybody was trying to run away from this inferno, and the expected communicational value of this “signal” soon became totally lost.
I cannot imagine any MBTA official, or the “acoustic” engineers who “designed” this system to deliberately expect that such an aberration can actually work, or give credit to a poorly designed emergency system like this one. On the other hand, they might have their ears in such a poor condition that they themselves don’t realize how harmful this is to their passengers.
Anyway, if you happen to be in Boston, have to take your 5 o’clock T and find yourselves in the middle of this incredible cacophony, you’d better carry some really heavy duty hearing protectors or prepare to sue the company.
This way they might have to redesign the entire system...