American Technology Corporation

Other

Lrad Corporation

Dolby Laboratories Licensing Corporation

Parametric Sound Corporation

James J Croft, Iii

Elwood Grant Norris

Joseph O Norris

Michael E Spencer

Jeevan G Bank

Vaughn W North

Wensen Liu

David Graebener

Terry Conrad

Michael John Smithers

Alan Robert Selfridge

Garth Norman Showalter

Pierre Khuri-Yakub

Philip R Clements

Robert C Williamson

Kenneth Lawrence DeVries

Clifton Wynn Thompson

Boaz Shalev

Norbert P Daberko

A dual wave-column, dual-driver loudspeaker enclosure is described. The two drivers are cross-coupled through their respective front and back sides by two single exit wave-columns. At the &#xbc; wavelength frequency of the waveguide length, both drivers resonate with the waveguides, and cone motion is minimized while output is maximized. At the &#xbd; wavelength frequency, the front wave of the first driver is in-phase with, the rear wave of the second driver such that the output is increased, reinforced, and smoothed at that frequency. At the &#x2153; wavelength frequency, the two wave-column mouth outputs exhibit acoustic mutual coupling, which boosts acoustic output and reduces cone motion at the critical maximum displacement frequency.

Multi-driver loudspeaker with cross-coupled dual wave-columns

A signal processing system for controlling a lower frequency acoustic range of an acoustic output of a loudspeaker system. The system includes an input to receive at least a first channel audio signal, corresponding to the acoustic output of at least one loudspeaker with at least one electro-acoustic transducer with a vibratile diaphragm. The signal processing system includes at least one transpositional gain controller processor for transposition of at least a portion of the amplitude of at least one band of frequencies in a lower frequency audio signal range of the audio signal, to an increased gain in at least one transpositional target frequency in the lower frequency audio signal range. The transpositional gain controller processor includes at least one of at least one, static or dynamic, transpositional gain controller. The system may include at least one additional signal processor, supporting preservation of a perceived fidelity of the acoustic output.

Signal processor for loudspeaker systems for enhanced perception of lower frequency output

In a low frequency transducer system a multi-compression chamber, an inverse horn structure is employed in combination with a resonance-distortion filter chamber. The filter chamber effectively expands the effective enclosure volume at low frequencies and connected to one of the compression chambers filter parasitic resonances and distortion and allowing the system to more efficiently reproduce low frequencies while being able to use smaller diameter transducers and maintaining good system sensitivity. Compression chambers are organized for constant or continuous compression on a section-by-section basis throughout the inverse horn system.

Inverse horn loudspeakers

A loudspeaker system with a transducer and an enclosure with at least one resonant chamber, including a resonant-chamber resonance frequency, at which a displacement characteristic of a vibratile diaphragm of the transducer has a minimum. The loudspeaker system further includes a multi-mode signal processor with a set of signal processes wherein in one example, a variable gain, frequency selective dynamic filter reduces the gain in a high displacement frequency range upon an output in the frequency range exceeding an overload amplitude threshold. The gain reduction is compensated for by complimentary frequency generating signal processes, including at least one of a harmonics generator and a transpositional gain controller, with the signal processor adapted to match the resonant chamber enclosure by substantially maintaining or increasing acoustic output at the resonant chamber resonance and generating harmonics associated with fundamental frequencies in the gain reduced frequency range to maintain a perception of tonal quality and physical bass impact, increasing low frequency capability while minimizing audible overload distortion.

Loudspeaker enclosure system with signal processor for enhanced perception of low frequency output

The invention provides a planar-magnetic transducer with a frame and a primary magnet row structure of elongated magnets adjacent and air gapped from a first surface side of a mobile portion of a thin film or thin structure diaphragm with conductive traces incorporated with the diaphragm. An additional pair of magnetic sources attached to the frame outside of the vibratable region of the diaphragm and mounted above the plane of the opposite, second surface side of the diaphragm to enhance magnetic energy near the second surface side of the film diaphragm, without any magnet rows attached directly in front of the second surface side of the vibratable region of the diaphragm between the additional pair of magnetic sources. The additional magnetic sources can increase the drive force to the outer portions of the vibratable diaphragm, or across the diaphragm, to provide more control near the termination edge of the diaphragm and to create a more planar displacement of the diaphragm and increase transducer efficiency.

Planar-magnetic transducer with improved electro-magnetic circuit

A single-ended planar transducer device for generating a sound signal based on an electrical signal comprising at least two primary rows of primary magnets, at least one return row of at least one return structure, a diaphragm, a conductive trace formed on the diaphragm, and a frame. The frame supports two primary rows to define at least one core set comprising no more than two primary rows. A primary magnetic field is established between the primary rows in the at least one core set. The frame supports at least one return row adjacent to the at least one core set. A return magnetic field is established between each return row and any primary row adjacent thereto. A first portion of the trace is arranged at least partly within each primary magnetic field and a second portion of the trace is arranged at least partly within each return magnetic field.

Magnetically one-side driven planar transducer with improved electro-magnetic circuit

A signal processing system for use in a multi-channel audio system having a plurality of power amplifier channels connected to a plurality of loudspeakers and power amplifiers, configured to receive and reproduce audio signals through the loudspeakers, and at least a first channel of the plurality of power amplifier channels amplifying a first audio signal, comprises a processor responsive to a signal level threshold applicable to at least said first channel, such that at and above the signal level threshold, the first audio signal in the first channel is amplitude limited and a portion of at least the first audio signal is mixed into at least a second channel. The amplitude limiting and signal mixing is configured so as to reduce introduction of at least one of: a) audible tonal distortion; and b) perceivable spatial distortion; of a sonic presentation due to said limiting and signal mixing.

Dynamic power sharing in a multi-channel sound system

A system and methods for distortion reduction in a non-linear audio system are disclosed. A method includes the operation of defining a non-linear system transfer function which relates a system electronic input signal with a system acoustic output over a range in which the system acoustic output is in a transition between non-saturated and saturated conditions in a medium in which the system acoustic output of the non-linear audio system is broadcast. A preprocessing transfer function is created that is the inverse of the non-linear system transfer function. The preprocessing transfer function is applied to the system electronic input signal to reduce the level of harmonic distortion at the system acoustic output.

Audio distortion correction for a parametric reproduction system

A method is disclosed for increasing a parametric output of a parametric loudspeaker system. The method can include the operation of providing multiple ultrasonic frequency emission zones that output signals in a frequency band. The phase relationships of the ultrasonic frequency emission zones can be correlated and controlled to increase phase coherence between each ultrasonic frequency emission zone to maximize parametric output. Correlating and controlling the phase relationships can include offsetting a frequency of a carrier signal applied to each emission zone from a resonant frequency of each emission zone in view of a rate of change of phase of each emission zone in a vicinity of each resonant frequency. Ultrasonic energy from the ultrasonic frequency emission zones can be generated, using the correlated phase relationship to increase the parametric output.

Parametric loudspeaker with improved phase characteristics

A system and method for varying the directionality of an acoustic output of a loud hailing and warning device is disclosed. The method includes the operation of placing a sliding high-pass filter in a signal path of a transducer array having a frequency-dependant dispersion characteristic. A control is provided that varies a lower cutoff frequency of the sliding high-pass filter. The lower cutoff frequency of an electronic audio signal is variably controlled and sent to the transducer array to variably control the directionality of the acoustic output of the loud hailing and warning device.

Variable directivity loud hailing device

A parametric loudspeaker system using improved modulators to compensate for the non-linearity of the parametric process in air when driving the air at saturation levels and below saturation levels. The parametric loudspeaker uses a pre-processed single sideband modulator that offers ideal linearity as characterized by square root pre-processed double sideband modulators but with a lower carrier frequency and without the wide bandwidth requirements. By eliminating some or all of the lower sideband the carrier frequency can be reduced without producing sideband frequencies in the audible range. Lower operational frequencies result in greater translation efficiency and greater output capability before reaching the saturation limit of air. A pre-processor minimizes the effects of saturation limits for double sideband, truncated double sideband or single sideband processing to achieve superior output.

Modulator processing for a parametric speaker system

A parametric loudspeaker system and method for reducing distortion in a decoupled audio wave by creating a double sideband parametric ultrasonic signal that substantially approximates a non-square-rooted modulation envelope and emitting a parametric ultrasonic wave that corresponds to the double sideband parametric ultrasonic signal from a parametric loudspeaker at a sufficient amplitude to drive the surrounding air into saturation.

Parametric audio system for operation in a saturated air medium

A method and system of producing a parametric ultrasonic wave to be decoupled in air to create a decoupled audio wave that closely corresponds to an audio input signal. The method is comprised of ascertaininga linear response over a predefined frequency range of an acoustic output of an electro-acoustical emitter to be used for parametric ultrasonic output. A parametric ultrasonic processed signal is then created by adjustinglinear parameters of at least one sideband frequency range of a parametric ultrasonic signal to compensate for the linear response of the acoustic output of the electro-acoustical emitter such that when the parametric ultrasonic processed signal is emitted from the electro-acoustical emitter, the parametric ultrasonic wave is propagated, having sidebands that are closely matched at least at a predefined point in space over the at least one sideband frequency range.

Method of adjusting linear parameters of a parametric ultrasonic signal to reduce non-linearities in decoupled audio output waves and system including same

A directional acoustic device configured for producing a directional output along an acoustic axis, including at least one transducer configured to create at least two wave trains which are directed along differing pathways by at least one wave guide, and so disposed that in directions more than ninety degrees off the acoustic axis the SPL of the output is greatly diminished by cancellation effects between the wave trains; improvement over previous gradient and quarter-wave pipe directional systems being enabled.

Directional acoustic device

A speaker device for emitting subsonic, sonic or ultrasonic compression waves comprising a generally hollow drum, a rigid emitter plate attached to the drum, and a plurality of apertures formed within the plate which are covered by a thin piezoelectric film disposed across the emitter plate. A pressure source is coupled to the drum for developing a biasing pressure with respect to the thin film at the apertures to distend the film into an arcuate emitter configuration capable of constricting and extending in response to variations in the applied electrical input at the piezoelectric film to thereby create a compression wave in a surrounding environment. Parametric ultrasonic frequency input is supplied to the piezoelectric film to propagate multiple ultrasonic frequencies having a difference component corresponding to the desired subsonic, sonic or ultrasonic frequency range.

Growing community of inventors

Poway, CA, United States of America

James J Croft, Iii