Abstract: A self-orienting, directionally sensitive particle velocity transducer with an axially magnetized magnet which, displaced by gravity, floats off-center in a chamber filled with ferromagnetic fluid. Wire coils affixed coaxially to the chamber ends asymmetrically intersect the magnet's flux lines. Axial chamber rotation results in gravitationally induced sideways movement of the magnet to maintain its equilibrium position. An impinging sound wave causes relative movement between the low inertia chamber-coil assembly and the high inertia magnet, thereby inducing a voltage in the coils--a relatively high voltage for vertical movement due to vertical assymetry, but a relatively low voltage for horizontal movement due to horizontal symmetry. Axial sensitivity is low because the ferromagnetic fluid filling the narrow gap between the magnet and the chamber ends resists relative axial movement and any induced voltages in the coils cancel.

Abstract: A vibratory ribbon speaker according to this invention as disclosed comprises a series of permanent magnets secured on opposite faces of a pair of soft iron bars mounted in edge-opposed, spaced-apart relation providing an air return flux path and a working air gap in which is suspended an elongated wavy or corrugated non-magnetic ribbon, several feet in length, flexibly and resiliently supported in said air gap at numerous spaced-apart stations along the ribbon length.