Note that this is, in fact, a gunshot detector. Image here: https://www.mapillary.com/app/?lat=37.530990957891&lng=-77.410916101132&z=19.00411711473014&pKey=3923230994594307&focus=photo&x=0.9615944380111534&y=0.5542417850325391&zoom=1.1807838435170073