[bgoated01]

Resonators like this are effectively changing the resonating properties of the tire so that the vibration of the tire isn't as effectively changed into sound. Tires have certain frequencies or tones that they amplify, and the resonators can remove some of that amplication by redirecting the energy into the resonators themselves. It's equivalent roughly to adding a second pendulum to the bottom of a swinging pendulum. The first pendulum doesnt swing as far because energy is transferred into the second pendulum. The first pendulum being the one that effectively radiates noise (the tire), the final effect is less radiated sound. Since this treatment controls noise at its source, it will reduce noise for all parties.

Source: I worked on a resonator-based noise control solution as part of my Masters degree.