A system comprising: a proof mass assembly comprising: a proof mass (112, 312); a resonator connection structure (116, 316), wherein the resonator connection structure (116, 316) extends parallel to a long axis; a hinge flexure (114, 314) configured to connect the proof mass (112, 312) to the resonator connection structure (116, 316), wherein the proof mass (112, 312) rotates about the hinge flexure (114, 314) in response to an acceleration of the system parallel to the long axis of the resonator connection structure (116, 316); and a first resonator (120, 320, 420) configured to connect the proof mass (112, 312) to the resonator connection structure (116, 316), wherein the first resonator (120, 320, 420) comprises: a first mechanical beam (124a, 424a) extending parallel to the long axis; and a second mechanical beam (124b, 424b) extending parallel to the long axis; and processing circuitry configured to: receive, from the first resonator (120, 320, 420), one or more electrical signals indicative of a frequency of the first mechanical beam (124a, 424a) and a frequency of the second mechanical beam (124b, 424b); determine, based on the one or more electrical signals, the frequency of the first mechanical beam (124a, 424a) and the frequency of the second mechanical beam (124b, 424b); and calculate, based on the frequency of the first mechanical beam (124a, 424a) and the frequency of the second mechanical beam (124b, 424b), an acceleration of the proof mass assembly, characterized in that the first mechanical beam (124a, 424a) comprises a first added mass (113, 313, 462", 464") located at a point along the long axis and the second mechanical beam (124b, 424b) comprises a second added mass (113, 313, 462", 464") located at the point along the long axis. a proof mass assembly comprising: a proof mass (112, 312); a resonator connection structure (116, 316), wherein the resonator connection structure (116, 316) extends parallel to a long axis; a hinge flexure (114, 314) configured to connect the proof mass (112, 312) to the resonator connection structure (116, 316), wherein the proof mass (112, 312) rotates about the hinge flexure (114, 314) in response to an acceleration of the system parallel to the long axis of the resonator connection structure (116, 316); and a first resonator (120, 320, 420) configured to connect the proof mass (112, 312) to the resonator connection structure (116, 316), wherein the first resonator (120, 320, 420) comprises: a first mechanical beam (124a, 424a) extending parallel to the long axis; and a second mechanical beam (124b, 424b) extending parallel to the long axis; and a proof mass (112, 312); a resonator connection structure (116, 316), wherein the resonator connection structure (116, 316) extends parallel to a long axis; a hinge flexure (114, 314) configured to connect the proof mass (112, 312) to the resonator connection structure (116, 316), wherein the proof mass (112, 312) rotates about the hinge flexure (114, 314) in response to an acceleration of the system parallel to the long axis of the resonator connection structure (116, 316); and a first resonator (120, 320, 420) configured to connect the proof mass (112, 312) to the resonator connection structure (116, 316), wherein the first resonator (120, 320, 420) comprises: a first mechanical beam (124a, 424a) extending parallel to the long axis; and a second mechanical beam (124b, 424b) extending parallel to the a first mechanical beam (124a, 424a) extending parallel to the long axis; and a second mechanical beam (124b, 424b) extending parallel to the long axis; and processing circuitry configured to: receive, from the first resonator (120, 320, 420), one or more electrical signals indicative of a frequency of the first mechanical beam (124a, 424a) and a frequency of the second mechanical beam (124b, 424b); determine, based on the one or more electrical signals, the frequency of the first mechanical beam (124a, 424a) and the frequency of the second mechanical beam (124b, 424b); and calculate, based on the frequency of the first mechanical beam (124a, 424a) and the frequency of the second mechanical beam (124b, 424b), an acceleration of the proof mass assembly, characterized in that the first mechanical beam (124a, 424a) comprises a first added mass (113, 313, 462", 464") located at a point along the long axis and the second mechanical beam (124b, 424b) comprises a second added mass (113, 313, 462", 464") located at the point along the long axis. receive, from the first resonator (120, 320, 420), one or more electrical signals indicative of a frequency of the first mechanical beam (124a, 424a) and a frequency of the second mechanical beam (124b, 424b); determine, based on the one or more electrical signals, the frequency of the first mechanical beam (124a, 424a) and the frequency of the second mechanical beam (124b, 424b); and calculate, based on the frequency of the first mechanical beam (124a, 424a) and the frequency of the second mechanical beam (124b, 424b), an acceleration of the proof mass assembly, characterized in that the first mechanical beam (124a, 424a) comprises a first added mass (113, 313, 462", 464") located at a point along the long axis and the second mechanical beam (124b, 424b) comprises a second added mass (113, 313, 462", 464") located at the point along the long axis.