Active room compensation in loudspeaker system
First Claim
1. A method for compensating for acoustic influence of a listening room on an acoustic output from an audio system including at least a left and a right loudspeaker, the method comprising:
- determining a left frequency response LPL as a function between a signal applied to the left speaker and a resulting power average in a listening position,determining a right frequency response LPR as a function between a signal applied to the right speaker and a resulting power average in the listening position,designing a left compensation filter FL based on the left frequency response and a left target function, the left target function comprising a desired function between frequency and gain for a general room,designing a right compensation filter FR based on the right frequency response and a right target function,determining a filtered mono response LPM according to LPL*FL+LPR*FR,determining a filtered side response LPS according to LPL*FL−
LPR*FR, wherein LPL is the left frequency response, LPR is the right frequency response, FL is the left compensation filter and FR is the right compensation filter,designing a mono compensation filter FM based on the filtered mono response LPM and a target function,designing a side compensation filter FS based on the filtered side response LPS and a target function, andduring playback;
receiving left and right input signals, andapplying the left compensation filter to a left filter input, applying the right compensation filter to a right filter input, applying the mono compensation filter to a mono signal based on the left and right input signals, and applying the side compensation filter to a side signal based on the left and right input signals.
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Abstract
A method for compensating for acoustic influence of a listening room on an acoustic output from an audio system including at least a left and a right loudspeaker, the method comprising determining a left frequency response and a right frequency response, designing left and right compensation filters, and during playback applying the left and right filters to left and right input signals. The method further includes determining mono and side responses and designing mono and side compensation filters, and, during playback, applying the mono compensation filter to a mono signal based on the left and right input signals, and applying the side compensation filter to a side signal based on the left and right input signals. The filters are thus combined to provide left and right output signals which have been left/right filtered and mono/side filtered.
22 Citations
33 Claims
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1. A method for compensating for acoustic influence of a listening room on an acoustic output from an audio system including at least a left and a right loudspeaker, the method comprising:
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determining a left frequency response LPL as a function between a signal applied to the left speaker and a resulting power average in a listening position, determining a right frequency response LPR as a function between a signal applied to the right speaker and a resulting power average in the listening position, designing a left compensation filter FL based on the left frequency response and a left target function, the left target function comprising a desired function between frequency and gain for a general room, designing a right compensation filter FR based on the right frequency response and a right target function, determining a filtered mono response LPM according to LPL*FL+LPR*FR, determining a filtered side response LPS according to LPL*FL−
LPR*FR, wherein LPL is the left frequency response, LPR is the right frequency response, FL is the left compensation filter and FR is the right compensation filter,designing a mono compensation filter FM based on the filtered mono response LPM and a target function, designing a side compensation filter FS based on the filtered side response LPS and a target function, and during playback; receiving left and right input signals, and applying the left compensation filter to a left filter input, applying the right compensation filter to a right filter input, applying the mono compensation filter to a mono signal based on the left and right input signals, and applying the side compensation filter to a side signal based on the left and right input signals. - View Dependent Claims (2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14, 15, 16, 17, 18, 19, 20, 21, 22, 30)
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23. A method for removing dips in a frequency response between a signal applied to a speaker and a resulting power average in a listening position, comprising:
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providing a reference by smoothing the response with a reference smoothing width, comparing the response and the reference, and for each frequency, selecting the maximum of the response and the reference as dip removed response. - View Dependent Claims (24, 25, 26, 27, 28, 29)
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31. An audio system including:
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at least a left and a right loudspeaker arranged in a listening room; at least one microphone arranged in a listening position; a signal processing system for compensating for acoustic influence of the listening room on an acoustic output from the loudspeakers, said signal processing system being configured to; apply a test signal to the left speaker, determine a power average based on a signal measured in the microphone, and determine a left frequency response LPL between the test signal and the power average, apply a test signal to the right speaker, determine a power average based on a signal measured in the microphone, and determine a right frequency response LPL between the test signal and the power average, design a left compensation filter FL, and design a right compensation filter FR; wherein the signal processing system is further configured to; determine a filtered mono response LPM according to LPL FL+LPR FR, determine a filtered side response LPS according to LPL FL−
LPR FR, wherein LPL is the left response, LPR is the right response, FL is the left filter and FR is the right filter,design a mono compensation filter FM based on the filtered mono response LPM and a target function, the target function comprising a desired function between frequency and gain for a general room, and design a side compensation filter FS based on the filtered side response LPS and a target function; and wherein the system further comprises a filtering system configured to, during playback; receive a left signal input and a right signal input, apply the left compensation filter to a left filter input, apply the right compensation filter to a right filter input, apply the mono compensation filter to a mono signal based on the left and right input signals, and apply the side compensation filter to a side signal based on the left and right input signals. - View Dependent Claims (32, 33)
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Specification