The advent of 3D printing brings about the possibilities of microlattices as advanced and novel sound absorbers. Microlattices are defined as periodic cellular solids with submillimeter sized features (such as struts, shells, or plates) spatially arranged in a three dimensional manner. Advantages of microlattices over traditional sound absorbers include them being fully designable, customizable, and with the potential for multifunctionalities. Herein, the sound absorption properties and the corresponding absorption mechanisms of several types of microlattices are investigated and presented. The first study focuses on four types of metallic face-centred cubic based plate and truss microlattices. Impedance tube measurements reveal that all of the microlattices display absorption curves with characteristic resonance peaks. Sound absorption mechanisms of microlattices are proposed to be based on the multilayered perforated absorber principle. Characteristics of absorption coefficients are found to be essentially geometry limited by the pore and cavity morphologies. Following this, we have next optimized the pore and cavity geometries for a novel polymeric plate-truss hybrid microlattice for broadband absorption. This structurally optimized structure presents excellent broad-band absorption with an averaged experimental absorption coefficient of 0.77 across a broad frequency range from 1000 to 6300 Hz. Extensive simulation and experiments reveal absorption mech-anisms to be based on viscous flow, thermal and structural damping dissipations while broadband capabilities are on multiple resonance modes working in tandem. For their porous nature, the microlattices also dual function as energy absorbers under compressive impact. High specific energy absorptions are revealed for the metallic microlattices, whilst the polymeric one displays high strain recoverability and retains its sound absorption capability. Overall, we present a new concept on the specific structural design and materials selection for microlattices with excellent sound absorbing properties and additional functionalities.