Harman International Industries, Inc.

University of Utah Research Foundation

Russell H Lambert

Douglas J Button

James M Kirsch

Jeffrey L Hutchings

Josh Hunsaker

Ajay Sundaram Iyer

V John Mathews

Meenakshi Barjatia

Shreyas Srikanth Payal

A loudspeaker parameter system for vented box driver excursion modeling, may include a loudspeaker driver having a conductor, a magnet and a diaphragm. The system may further include a processor for excursion modeling configured to receive an input signal, determine a voltage level of the input signal, an enclosure having a resonant port, estimate port parameters including at least one of an acoustic resistance or acoustic mass, and apply a voltage limit based on the vented box excursion model utilizing the port parameters.

Nonlinear port parameters for vented box modeling of loudspeakers

A thermal model system for estimating a voice coil temperature of a loudspeaker that has frequency dependent parameters to model thermal behavior of the loudspeaker may include a loudspeaker having a voice coil and a magnet, and a thermal model configured to have multiple frequency dependent thermal circuits including the voice coil and the magnet that determine a voice coil temperature which is used to limit input to the loudspeaker to prevent thermal overload of the loudspeaker.

Constrained nonlinear parameter estimation for robust nonlinear loudspeaker modeling for the purpose of smart limiting

A software application uncovers phase spreading that corrupts the linear response filters of a nonlinear system and executes a corrective algorithm that generates true-phase filters of the response over all nonlinear orders used in the analysis. The application first outputs a signal with logarithmically changing frequency, as a stimulus to generate a set of Farina harmonic response filters. The application then constructs an identity model and excites the identity model with an identical input under identical conditions, to generate a set of spreading function filters. The application computes the inverse of the spreading function filters and convolves the inverse spreading function filters with the Farina harmonic response filters to generate a set of spreading corrected filters. Finally, the application constructs the unmixing Chebyshev matrix and convolves the spreading correction filters with the unmixing Chebyshev matrix to remove the spreading and generate harmonically pure and phase-corrected filters.

Techniques for improving swept sine analyses

A loudspeaker real-time state variable prediction system may include a loudspeaker having a voice coil and a magnet, and a non-linear excursion model configured to estimate non-linear excursion of the loudspeaker. The system may further include a thermal model configured to utilize thermal parameters and frequency based on at least one thermal property of the loudspeaker, and a gain adjustment thermal limiter configured to apply a gain reduction an incoming audio signal to protect the loudspeaker from thermal overload.

A non-linear excursion estimations system for estimating non-linear excursion of a loudspeaker may include a loudspeaker having a force transducer, and a controller programmed to limit excursion of the loudspeaker by modeling at least one constrained nonlinearity curve based on an asymptote outside of a safe operating area (SOA) nonlinearly curve of the loudspeaker.

One or more embodiments set forth an audio presence detection system, with a memory that includes an acoustic presence detection application, and a processor that executes the acoustic presence detection application. The audio presence detection system receives a first input signal associated with a first speaker, and receives a second input signal associated with a first microphone. The audio presence detection system generates, via an adaptive filter, a first estimation signal based on at least the first input signal and an impulse response associated with a room related to the first speaker and the first microphone. The audio presence detection system computes a first error signal based on the second input signal and the first estimation signal. The audio presence detection system determines that an object is present within a space based on a magnitude associated with the first error signal relative to a first threshold level.

Acoustic presence detector

A software application characterizes a nonlinear system by applying a series of test signals at full power and performing an algorithm on the resulting outputs to determine the true linear response and the order-separated outputs. The application generates a baseline test signal, multiplied by a gain factor. The application inputs the test signal to the system to produce a response. The application then generates another test signal by multiplying the baseline signal by a different gain factor. The application iterates generating test signals by multiplying by differing gain factors. The application then constructs a Vandermonde matrix of the gain factors, computes the inverse Vandermonde matrix, and convolves the inverse Vandermonde matrix with a matrix of the system responses to each of the test signals. The elements of the resulting convolution represent the order-separated outputs including the linear response output of the nonlinear system at full power.

Technique for determining nonlinear order-separated responses of nonlinear systems including linear response at system typical input levels

In one embodiment, a pre-correcting engine generates a pre-corrected signal that may be used to mitigate air path distortions in sounds generated by loudspeaker systems that include loudspeakers coupled to waveguides. In operation, the pre-correcting engine virtually propagates a target signal in a reverse direction from the output of the waveguide to the output of a driver. Notably, the pre-correcting engine implements a propagation distortion compensation model that, when applied to the target signal, corrects for the effects of air path distortions on the target signal. The pre-correcting engine then transmits the pre-corrected signal to the driver. As the driver drives the waveguide based on the pre-corrected signal, effects of the pre-corrected distortions negate effects of air path distortions and the loudspeaker system generates high-fidelity sounds. By contrast, conventional loudspeaker systems that drive the waveguide based on the target signal typically generate lower fidelity sounds that include air path distortions.

Compensation of air path distortions using backpropagation

An electronic hearing protector includes an ear cup assembly comprising a front exterior microphone that provides a front microphone signal and a rear exterior microphone that provides a rear microphone signal. A processor receives and digitizes the front microphone signal and the rear microphone signal, and provides a front channel signal and a rear channel signal indicative thereof respectively. A filter receives the rear channel signal and has a cut-off frequency value that provides a high-frequency roll-off and a notch at a notch filter frequency value that is less than the cut-off frequency value, where the filter provides a filtered signal. A first signal indicative of the front channel signal and a second signal indicative of the filtered signal are summed, and a signal indicative of the summed signal is provided to a speaker within the ear cup that provides an audio signal within the first ear cup indicative of the summed signal.

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Highland, UT, United States of America

Russell H Lambert