A polarizer disposed between a transducer and a surface in which acoustic waves propagate can be used to filter out certain types of acoustic energy. For example, the polarizer can be used with a shear-polarized transducer to pass shear waves and filter out compressional waves that may interact with water, thereby improving water rejection. In some examples, the polarizer can include one or more layers of piezoelectric material with a poling direction different than (e.g., orthogonal to) the poling direction of the transducer. Energy of compressional waves may be extracted by one or more external electric circuits. In some examples, the polarizer can be a magneto-elastic polarizer. In some examples, the polarizer can be a mechanical polarizer.