The Landau theory of Fermi liquids provides a phenomenological theory of fermions with repulsive interactions at low temperature. One of the first predictions of this theory was the existence of "zero sound" waves, plane waves with sound-like dispersion at low temperatures. Holography provides a tool for studying toy models of strongly coupled condensed matter theories. Many holographic condensed matter models exhibit "holographic zero sound" (HZS), which are also modes with sound-like dispersion that exist at low temperature. This talk will describe HZS modes in a theory dual to a backreacted, spacetime-filling brane, with attenuation behaving remarkably similar to zero sound in Fermi liquids. The existence of HZS raises the question of whether real strongly coupled systems, such as graphene or high-temperature superconductors, support low temperature sound modes. If so, then the properties of HZS may give important insights into the effective description of such materials. Slides can be found here.