One embodiment provides a waveguide for controlling sound directivity of high frequency sound waves generated by a speaker driver. The waveguide is positioned in front of the speaker driver. The waveguide comprises one or more ridge areas, one or more recess areas, and one or more smooth surfaces. Each smooth surface connects a ridge area to a recess area to create a smooth transition between the ridge area and the recess area without any seams or sharp transitions. The waveguide shapes propagation of the sound waves to provide a smooth off-axis frequency response for the sound waves.

The invention discloses a novel passive sound transformer, either a sound-booster or a sound-silencer, embodied as an acoustic waveguide, a specific shape of which provides for either amplifying the intensity of acoustic waves at the expense of both the heat energy and the concomitant turbulence of moving fluid wherein the amplified intensity of the acoustic waves is manifested as sound loudness boosting or, contrarywise, transforming the wave power of elastic waves into the heat of the ambient fluid.

A component for manipulating an input shockwave. The component includes a body comprising a first material. The body defines a cavity for manipulating the input shockwave so to produce a manipulated shockwave. The cavity comprises an input for receiving the input shockwave incident upon the component and an output for outputting the manipulated shockwave from the cavity. The cavity contains a second material having a shock-impedance that is lower than a shock-impedance of the first material.

Provided is a throat and a speaker system that can properly correct a path length of a sound wave. A throat according to an embodiment includes a first side wall, a second side wall, a third side wall, and a fourth side wall. A third opposing surface of the third side wall and a fourth opposing surface of the fourth side wall are each formed into a curved surface having a convex portion and a concave portion. The convex portion and the concave portion are so disposed as to oppose each other, and the convex portion and the concave portion are so disposed as to oppose each other. Amplitudes of the curved third opposing surface and the curved fourth opposing surface gradually decrease along a direction from a reference center line to a first opposing surface or a second opposing surface.

One embodiment provides an omnidirectional loudspeaker comprising a first axisymmetric reflector, a second axisymmetric reflector, a sound source in the first axisymmetric reflector or the second axisymmetric reflector, and a horn including a straight section and a growth section extending from a distal end of the straight section. The growth section comprises one or more curves that are scaled with a radial coordinate and that expands sound waves generated by the sound source.

Provided is a throat and a speaker system that can properly correct a path length of a sound wave. A throat according to an embodiment includes a first side wall, a second side wall, a third side wall, and a fourth side wall. A third opposing surface of the third side wall and a fourth opposing surface of the fourth side wall are each formed into a curved surface having a convex portion and a concave portion. The convex portion and the concave portion are so disposed as to oppose each other, and the convex portion and the concave portion are so disposed as to oppose each other. Amplitudes of the curved third opposing surface and the curved fourth opposing surface gradually decrease along a direction from a reference center line to a first opposing surface or a second opposing surface.

Defining critical spacing is necessary for steering of parametric audio. Comparing steering measurements both with and without a waveguide leads to a conclusion that the diffuse phyllotactic grating lobe contributes audio and is to blame for poor steering. In addition, the waveguide needs to function with correct phase offsets to achieve the steering required for performance. Arranging tubes so that the array configuration changes from rectilinear to another distribution is useful when the waveguide is short of critical spacing or constrained for space. Array designs may also capitalize on rectilinear transducer design while having the benefits of a transducer tiling that has irrational spacing to promote the spread of grating lobe energy.

An acoustical horn is disclosed which is configured to re-direct spherical acoustic wave fronts radiated from a transducer with a minimum amount of distortion. The acoustical horn includes top and bottom portion which are asymmetrically-shaped with respect to each other.

Aspects of the present invention relate to an active noise system (4), a vehicle (1) with an active noise system (4), a method for controlling an active noise system (4), a computer program for controlling an active noise system (4) and an active noise controller (40). The wading detection system (3) includes sensors (30, 31, 32, 33) for detecting a wading depth and a wading detection controller (34). The active noise system (4) includes speakers (41, 42) for modifying the exhaust noise emitted from the vehicle (1). The wading detection controller (34) is operable to detect or anticipate a predetermined wading depth (W.sub.1, W.sub.2) at which the speakers (41, 42) will come into contact with the water. The active noise controller (40) is configured to deactivate the speakers (41, 42) when the predetermined wading depth (W.sub.1, W.sub.2) is detected or anticipated by the wading detection controller (34).

There is provided a horn device for a railcar capable of delivering horn sound to a long distance in a traveling direction and being less likely to spread sound in a car width direction. A horn device for a railcar according to one aspect of the present invention includes: a whistle portion that is supplied with compressed air to make horn sound in a traveling direction; a duct located in the traveling direction of the whistle portion and having an opening portion at an end portion in the traveling direction; and at least one partition plate that is disposed perpendicularly to a car width direction, extends in a car longitudinal direction, and divides the interior of the duct.