A broadband noise barrier includes Helmholtz-type resonator cavities. The barrier has a core section made up of one or more layers of cellular cavities of varying sizes sandwiched between a substantially planar face section placed toward a noise source, and an impermeable, substantially planar base section placed away from the noise source. The face section has apertures of specified sizes to permit disturbed air from the noise source to interact with the cavities in the core section. The variable cavity sizes permit resonant interactions with selected frequencies commonly associated with traffic noise, thus providing broadband acoustic absorption. Since the performance of the system derives from the resonator configuration rather than the constitutive properties of the materials used, the structure requires neither special materials, unconventional manufacturing processes, nor thick, heavy panel structures. The barrier may include additional layers of porous, sound-absorbing material to provide additional acoustic performance, and, in the case of a multiple-layer core section, have cavity walls between the various layers misaligned to minimize secondary modes of acoustic transmission. In addition, a cap-like edge section tailored to reduce the noise associated with diffracted sound waves can be added to a top or side edge of the barrier.