An inventive accelerometer includes a proof mass and a pair of vibrating sensors. An excitation-and-detection circuit drives one sensor at resonant frequencies f1 and F1, with f1≠F1; a second excitation-and-detection circuit drives the other sensor at resonant frequencies f2 and F2, with f2≠F2. The vibrational modes driven at the frequencies f1 and f2 are the same for each sensor; the vibrational modes driven at the frequencies F1 and F2 are the same for each sensor. Compressive or tensile loads oppositely applied by the proof mass to the vibrating sensors cause a difference frequency ΔF=F1−F2 to vary monotonically with acceleration of the apparatus along a sensing axis, from which a measurement of acceleration can be generated.