Calculating and adjusting the perceived loudness and/or the perceived spectral balance of an audio signal
First Claim
1. A method for controlling a perceptual loudness of a digital audio signal, comprising:
- deriving modification parameters from the digital audio signal for modifying reproduction of the digital audio signal to reduce a difference between the perceptual loudness and a target loudness, the modification parameters comprising amplitude scale factors, each amplitude scale factor respectively operating in a frequency band of a plurality of frequency bands;
applying the modification parameters to the digital audio signal to reduce the difference between the perceptual loudness and the target loudness,wherein the perceptual loudness varies both with frequency and acoustic level;
wherein the method is performed by one or more computing devices.
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Abstract
The invention relates to the measurement and control of the perceived sound loudness and/or the perceived spectral balance of an audio signal. An audio signal is modified in response to calculations performed at least in part in the perceptual (psychoacoustic) loudness domain. The invention is useful, for example, in one or more of: loudness-compensating volume control, automatic gain control, dynamic range control (including, for example, limiters, compressors, expanders, etc.), dynamic equalization, and compensating for background noise interference in an audio playback environment. The invention includes not only methods but also corresponding computer programs and apparatus.
168 Citations
18 Claims
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1. A method for controlling a perceptual loudness of a digital audio signal, comprising:
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deriving modification parameters from the digital audio signal for modifying reproduction of the digital audio signal to reduce a difference between the perceptual loudness and a target loudness, the modification parameters comprising amplitude scale factors, each amplitude scale factor respectively operating in a frequency band of a plurality of frequency bands; applying the modification parameters to the digital audio signal to reduce the difference between the perceptual loudness and the target loudness, wherein the perceptual loudness varies both with frequency and acoustic level; wherein the method is performed by one or more computing devices. - View Dependent Claims (2, 3, 4, 5, 6)
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7. An apparatus for controlling a perceptual loudness of a digital audio signal, comprising:
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a subsystem, implemented at least partially in hardware that derives modification parameters from the digital audio signal for modifying reproduction of the digital audio signal to reduce a difference between the perceptual loudness and a target loudness, the modification parameters comprising amplitude scale factors, each amplitude scale factor respectively operating in a frequency band of a plurality of frequency bands; a subsystem, implemented at least partially in hardware that applies the modification parameters to the digital audio signal to reduce the difference between the perceptual loudness and the target loudness, wherein the perceptual loudness varies both with frequency and acoustic level. - View Dependent Claims (8, 9, 10, 11, 12)
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13. A non-transitory computer readable medium, storing software instructions for controlling a perceptual loudness of a digital audio signal, which when executed by one or more processors cause performance of the steps of:
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deriving modification parameters from the digital audio signal for modifying reproduction of the digital audio signal to reduce a difference between the perceptual loudness and a target loudness, the modification parameters comprising amplitude scale factors, each amplitude scale factor respectively operating in a frequency band of a plurality of frequency bands; applying the modification parameters to the digital audio signal to reduce the difference between the perceptual loudness and the target loudness, wherein the perceptual loudness varies both with frequency and acoustic level. - View Dependent Claims (14, 15, 16, 17, 18)
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Specification