The technology described in the document can be embodied in a speaker that includes one or more drivers, and an acoustic horn that includes a first side panel and a second side panel. Edges of the first and second side panels defines an opening for receiving acoustic outputs from one or more drivers. The speaker also includes a manifold disposed between the opening and the one or more drivers, the manifold including a plurality of acoustic passages for connecting the opening to each of the one or more drivers, and an adaptor. The adaptor is disposed between the manifold and the acoustic horn, and includes multiple apertures for the plurality of acoustic passages. The adaptor is configured to conform to a profile of the opening while maintaining a seal between the acoustic horn and the plurality of acoustic passages.

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.

A robotic cleaning appliance includes a housing to which is coupled a surface treatment item and a sensor assembly with first and second transducers and an acoustic interface. The first sonic transducer transmits sonic signals through an acoustic interface and out of a first acoustic opening toward a surface beneath the robotic cleaning appliance. The sonic signals reflect from the surface as corresponding returned signals received by the second sonic transducer via a second acoustic opening port of the acoustic interface. A first annular ring is defined around the first acoustic opening port and a second annular rings is defined around the second acoustic opening port. The annular ring attenuate direct path echoes between the acoustic opening ports. The first and second acoustic opening ports are coupled the first and sonic transducers, respectively, via first and second horns; and the horns are tilted from orthogonal with the surface.

A meta-material acoustic lens is based on multiple acoustic channels, having a helix shaped path arranged radially around the center. The helix pitch is a function of the helix radius. This changes the effective thickness of the lens as a function of its distance from the center of the lens. This create a phase shift gradient across the lens, which in turn changes the wavefront from one side of the lens to the other. This results with either a focusing lens, when the effective thickness decreases from center to edge of the lens, or a diverging lens when the effecting thickness decreases from center to edge of the lens.

A loudspeaker includes a horn and a compression driver in a shallow package for installation in a wall, e.g., a four inch wide wall. The total depth for this loudspeaker may be about 3 and inches. A low frequency speaker can be supported by the frame and dimensioned to be mounted in a wall. The horn can be supported by the frame positioned by the speaker. A compression driver is supported by the frame and acoustically connected to the horn. The horn acoustically loads the compression driver to provide a high dynamic output and a high sound pressure level with controlled acoustic directivity.