The Sonic Canyons are Primus' sensory organs, resonating structures allowing him to collect data from across the galaxy. This data is then processed into a more meaningful format by the Vector Sigma supercomputer. They are also the place where Siren was raised.
It appears the Sonic Canyons are on something like the wrong side of the tracks. Though it doesn't mention the Sonic Canyons by name, the Dreamwave More Than Meets The Eye guide books describes the part of Cybertron where Siren was raised as being a heavily industrialized section, known for producing tough and unsavory robots. These hard-scrabble robots are also characterized as being very "loud," "rough-and-tumble," and "raucous" by nature.