Bulk acoustic wave (BAW) resonators are mechanical oscillators that confine sound waves in a solid-state material. Due to their use in a wide range of classical devices, they have been engineered to exhibit high quality factors, and their interactions with electromagnetic fields have been extensively studied. Recently, BAW resonators have also rapidly developed into a promising platform for new quantum devices. In this talk, I present our work on interfacing them with microwave frequency superconducting circuits and using such circuit quantum acoustodynamics systems for quantum control and measurement of phonons.