Each of a pair of electrically conductive spiral coils is ensconced in a
disk-shaped matrix. The two coil-ensconced matrices are joined
face-to-face so as to sandwich between them a thin, non-magnetic elastic
layer. An electronic device is connected so that each coil and a
corresponding capacitor form an LC circuit. Electrification of the two LC
circuits results in the departing and returning, in oscillatory fashion,
of the two coil-ensconced matrices. This resonant behavior is both
electromagnetic and mechanical in nature. The intermittent
electromagnetic repelling is related to the LC circuitry and the
oppositely polar electrifications of the respective coils. The springy
mechanical activity is based on a spring-mass model and involves the
elasticity of the intermediate material and the entrainment of ambient
fluid. The dual oscillatory modes are merged at the same frequency
through tuning of either/both oscillatory mode(s). In many applications,
an inventive acoustic projector produces pressure waves underwater.