| MH ACOUSTICS, LLC Patent applications |
| Patent application number | Title | Published |
|---|
| 20100202628 | AUGMENTED ELLIPTICAL MICROPHONE ARRAY - In one embodiment, an audio system has a microphone array and a signal processing subsystem that processes audio signals generated by the microphone array to produce an output beampattem. The microphone array has (i) a plurality microphones arranged in a circular portion and (ii) a center microphone. The signal processing subsystem has (1) a decomposer that spatially decomposes the microphone audio signals to generate a plurality of eigenbeams and (2) a heamformer that generates the output beampattern as a weighted sum of the eigenbeams. By adding the center microphone, the audio system is able to provide some degree of control over the beamforming in the vertical direction as well as provide reduction of modal aliasin. | 08-12-2010 |
| 20090175466 | NOISE-REDUCING DIRECTIONAL MICROPHONE ARRAY - In one embodiment, a directional microphone array having (at least) two microphones generates forward and backward cardioid signals from two (e.g., omnidirectional) microphone signals. An adaptation factor is applied to the backward cardioid signal, and the resulting adjusted backward cardioid signal is subtracted from the forward cardioid signal to generate a (first-order) output audio signal corresponding to a beampattern having no nulls for negative values of the adaptation factor. After low-pass filtering, spatial noise suppression can be applied to the output audio signal. Microphone arrays having one (or more) additional microphones can be designed to generate second- (or higher-) order output audio signals. | 07-09-2009 |
| 20080260175 | Dual-Microphone Spatial Noise Suppression - Spatial noise suppression for audio signals involves generating a ratio of powers of difference and sum signals of audio signals from two microphones and then performing noise suppression processing, e.g., on the sum signal where the suppression is limited based on the power ratio. In certain embodiments, at least one of the signal powers is filtered (e.g., the sum signal power is equalized) prior to generating the power ratio. In a subband implementation, sum and difference signal powers and corresponding the power ratio are generated for different audio signal subbands, and the noise suppression processing is performed independently for each different subband based on the corresponding subband power ratio, where the amount of suppression is derived independently for each subband from the corresponding subband power ratio. In an adaptive filtering implementation, at least one of the audio signals can be adaptively filtered to allow for array self-calibration and modal-angle variability. | 10-23-2008 |
| 20080247565 | Position-Independent Microphone System - An audio system generates position-independent auditory scenes using harmonic expansions based on the audio signals generated by a microphone array. In one embodiment, a plurality of audio sensors are mounted on the surface of a sphere. The number and location of the audio sensors on the sphere are designed to enable the audio signals generated by those sensors to be decomposed into a set of eigenbeam outputs. Compensation data corresponding to at least one of the estimated distance and the estimated orientation of the sound source relative to the array are generated from eigenbeam outputs and used to generate an auditory scene. Compensation based on estimated orientation involves steering a beam formed from the eigenbeam outputs in the estimated direction of the sound source to increase direction independence, while compensation based on estimated distance involves frequency compensation of the steered beam to increase distance independence. | 10-09-2008 |
