Reduced latency low frequency equalization system
First Claim
1. A method to equalize frequency responses within a frequency range in a listening area, comprising:
- measuring frequency responses in the listening area generated by at least one acoustic transducer at an at least one listening point, resulting in a matrix of frequency responses;
inverting the matrix of frequency responses to determine a vector of correction filters for the at least one acoustic transducer;
performing a global magnitude equalization with respect to a target function on a resulting vector of frequency responses that is the result of multiplying the vector of correction filters with the matrix of frequency responses;
performing a global group delay equalization on the resulting vector of frequency responses; and
determining equalization filters in a time domain with an inverse Fourier transform of the resulting vector of frequency responses after performance of the global group delay equalization.
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Accused Products
Abstract
A frequency equalization system is provided that substantially equalizes the room frequency responses generated by at least one loudspeaker within a listening area so that the frequency responses in the listening area are substantially constant and flat within a desired frequency range with minimum signal latency. The frequency equalization system may use multiple microphones to measure the audio signals of one or more subwoofers to achieve an improved bass response that is flat across the relevant frequency range. The system employs an algorithm that is a closed-form, non-iterative, mathematical solution and features short computation time with reduced delays.
125 Citations
27 Claims
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1. A method to equalize frequency responses within a frequency range in a listening area, comprising:
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measuring frequency responses in the listening area generated by at least one acoustic transducer at an at least one listening point, resulting in a matrix of frequency responses;
inverting the matrix of frequency responses to determine a vector of correction filters for the at least one acoustic transducer;
performing a global magnitude equalization with respect to a target function on a resulting vector of frequency responses that is the result of multiplying the vector of correction filters with the matrix of frequency responses;
performing a global group delay equalization on the resulting vector of frequency responses; and
determining equalization filters in a time domain with an inverse Fourier transform of the resulting vector of frequency responses after performance of the global group delay equalization. - View Dependent Claims (2, 3, 4, 5, 6, 7, 8, 9, 10)
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11. A system of low frequency equalization of an audio signal within a listening area, comprising:
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an at least one means for measuring frequency responses in the listening area;
a signal block in receipt of the frequency responses that generates filter coefficients in response to the frequency responses;
a processor that implements at least one filter with the coefficients from the signal block to filter and processes the audio signal, where global equalization of the audio signal occurs in a time domain. - View Dependent Claims (12, 13, 14, 15, 16, 17, 18, 19)
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20. A system to equalize frequency responses within a frequency range in a listening area, comprising:
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means for measuring frequency responses in the listening area generated by at least one acoustic transducer at an at least one listening point, that results in a matrix of frequency responses;
means for inverting the matrix of frequency responses to determine a vector of correction filters for the at least one acoustic transducer;
means for performing a global magnitude equalization with respect to a target function on the resulting frequency responses that result after multiplying the vector of correction filters with the matrix of frequency responses;
means for performing a global group delay equalization on the resulting frequency responses; and
means to determine equalization filters in the time domain with an inverse Fourier transform of the resulting frequency responses. - View Dependent Claims (21, 22, 23, 24, 25, 26, 27)
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Specification