Traffic loops are those racetrack-shaped things you see in the road,
usually near intersections. They count cars and control traffic lights but
they are also very musical! These musical loops can be picked up with a
vehicle loop detector detector (VLDD). As one drives over the loops, the
metal mass of the vehicle changes their resonant frequencies to sound
like spaceships, theramins, birds, farts, even a sperm whale mating call! County workers can use
these to make sure loops are working normally. Non-county workers can hook them up
to subwoofers to make sure people's reactions are working normally.
4-pole (dual) loop at intersection
Car counting and speed determination on freeway.
Nearby loop used for testing.
The first experiments required a backseat full of test gear and some very tricky back-handed, rearview mirror adjustments while on the go.
Scope positioned to view in rearview mirror.
A "Big One"
Some sounds
The first circuit prototypes mimiced the test gear exactly, amplifying, heterodyning, detecting, etc.
Later iterations dispensed with some of the precision and focused more on "phat" sounds and stereo surround FX.
