A system for enhancing sound provided by at least a first and a second speaker driver symmetrically positioned relative to a first side and a second side of a listener. The system includes a enclosure structure having a first portion relative to the first speaker driver and the first side of the listener, including a material having a sound reflective surface, and positioned between a first area proximate the first speaker driver and a second area proximate the first side of the listener. The enclosure structure also has a second portion relative to the second speaker driver and the second side of the listener, including a material having a sound reflective surface, and positioned between a third area proximate the second speaker driver and a fourth area proximate the second side of the listener.

A system for enhancing sound provided by at least a first and a second speaker driver symmetrically positioned relative to a first side and a second side of a listener. The system includes a enclosure structure having a first portion relative to the first speaker driver and the first side of the listener, including a material having a sound reflective surface, and positioned between a first area proximate the first speaker driver and a second area proximate the first side of the listener. The enclosure structure also has a second portion relative to the second speaker driver and the second side of the listener, including a material having a sound reflective surface, and positioned between a third area proximate the second speaker driver and a fourth area proximate the second side of the listener.

A transducer assembly comprises a housing and a plurality of frequency steered transducer array elements. Each of the transducer array elements includes a plurality of piezoelectric elements. The frequency steered transducer array elements are configured to receive a transmit electronic signal including a plurality of frequency components and to transmit an array of sonar beams into a body of water. Each sonar beam is transmitted in an angular direction that varies according to one of the frequency components of the transmit electronic signal. The frequency steered transducer array elements are positioned within the housing in a fan-shaped configuration where an end section of at least two of the frequency steered transducer array elements are within an intersection range of each other.

Passively controlled acoustic metamaterials allow transmission of low amplitude acoustic (sound) waves having a resonance frequency and reflect waves having a substantially different frequency. Such materials also reflect waves having the resonance frequency when those waves have an amplitude exceeding a threshold. High amplitude resonance waves cause a resonance membrane contained in unit cells of the metamaterial to contact a rigid structure that is positioned at a longitudinal constraint distance from the resonance membrane in each unit cell. Such contact changes the resonance frequency of the membrane, thereby causing reflection of high amplitude waves. Actively controlled acoustic metamaterials include a ferromagnetic layer on the membrane and an electromagnetic positioned in each unit cell. Activation of the electromagnetic displaces the membrane and thereby shifts the resonance frequency of the membrane, on demand.

Passively controlled acoustic metamaterials allow transmission of low amplitude acoustic (sound) waves having a resonance frequency and reflect waves having a substantially different frequency. Such materials also reflect waves having the resonance frequency when those waves have an amplitude exceeding a threshold. High amplitude resonance waves cause a resonance membrane contained in unit cells of the metamaterial to contact a rigid structure that is positioned at a longitudinal constraint distance from the resonance membrane in each unit cell. Such contact changes the resonance frequency of the membrane, thereby causing reflection of high amplitude waves. Actively controlled acoustic metamaterials include a ferromagnetic layer on the membrane and an electromagnetic positioned in each unit cell. Activation of the electromagnetic displaces the membrane and thereby shifts the resonance frequency of the membrane, on demand.

Embodiments for one-way sound absorbing systems are described herein. In one example, a sound absorbing system includes a waveguide having open ends for receiving an incoming acoustic wave and wall portions defining a first port and a second port. A first electroacoustic absorber is mounted to the first port and is electrically connected to a shunting circuit, while a second electroacoustic absorber is mounted to the second port and is electrically connected to an open circuit. The sound absorption of the system is directional dependent.

A system for abating noise emanating from a kitchen electric appliance includes a base of a predetermined size, comprising a first instance of a noise reflecting material, so that said base is disposed underneath, supporting, and contiguous to said kitchen electric appliance, and a sleeve of a predetermined size, including a second instance of a noise reflecting material, one or more layers of at least one noise absorbing material, one closed end, and one open end, so that said one open end slides over said kitchen electric appliance and is contiguous to said base. Said noise is effectively abated by reverberating between said first instance of said noise reflecting material and said second instance of said noise reflecting material and is attenuated by said one or more layers of said at least one noise absorbing material.

A system for abating noise emanating from a kitchen electric appliance includes a base of a predetermined size, comprising a first instance of a noise reflecting material, so that said base is disposed underneath, supporting, and contiguous to said kitchen electric appliance, and a sleeve of a predetermined size, including a second instance of a noise reflecting material, one or more layers of at least one noise absorbing material, one closed end, and one open end, so that said one open end slides over said kitchen electric appliance and is contiguous to said base. Said noise is effectively abated by reverberating between said first instance of said noise reflecting material and said second instance of said noise reflecting material and is attenuated by said one or more layers of said at least one noise absorbing material.

A versatile metamaterial reflector is constructed of at least one pair of first and second reflectors each having a frequency-dependent phase shifting of a reflected waveform but together providing, between them, a constant phase difference. As few as two different types of reflectors (for example, a zero and relative pi radian reflector) are used to construct a variety of metamaterial reflectors.

A photoacoustic apparatus may include: a ring transducer configured to measure a photoacoustic signal generated from an object, and including a hollow space that is provided as a travel path of light and ultrasonic waves; a mirror part disposed along a light path of the light transmitted from the ring transducer, and configured to reflect the light transmitted from the ring transducer, and the ultrasonic waves generated from the object, and to adjust magnification of the mirror part according to a number of apertures of the photoacoustic apparatus; and a fluid tank including a transparent film that allows the photoacoustic signal to pass through the fluid tank, and accommodating a fluid, the ring transducer, and the mirror part inside the fluid tank.