Abstract: An electro-acoustic system including at least one directional transducer unit configured to generate a controlled sound radiation beam aimed at a reflection surface to bounce the sound off said reflection surface at a specular bounce point and thus create for a listener the perception that the sound originates from a sound impression area of said reflection surface.

Abstract: An acoustical bass absorber which reduces peak and dip frequency response errors caused by interference from naturally occurring axial standing waves in rectangular rooms. The apparatus uses two forms of simple harmonic resonance: pistonic diaphragm resonance and Helmholtz cavity resonance. The pistonic diaphragm resonance is achieved by attaching a rigid planar membrane to metal springs. The Helmholtz cavity resonance is achieved by constructing an enclosed chamber attached to an open cylindrical tube. Coupling these two dissipation devices leads to several-fold improvement in absorption and total room mode attenuation.

Abstract: A system to assist a skier in locating an unattached ski in powder snow after a fall includes an audible alarm member which is mounted on the ski, and a remote hand-held activator member held by the skier. The skier can trigger the alarm by operating a switch on the remote activator. The sound emitted by the alarm will allow the skier to locate the direction and position of the lost ski.