A mass is levitated with respect to a base, at least one of which is
comprised of a diamagnetic material, with the levitated mass also having a
permanent magnetic property. A second permanent magnet is optionally
configured such that it attracts the levitation mass away from the base to
overcome gravitational force on the mass, thereby suspending the mass over
the surface of the base. The mass is contained in a nonmagnetic,
non-shielding and optionally optically-transparent housing so as to limit
its excursion within a range of levitation positions. A position
measurement means such as a laser interferometer, capacitance detector, or
pickup coil is configured to measure positional deviations of the mass in
response to incident pressure wave, the output of which being an
electronic signal representing the pressure wave.
