Calculating and adjusting the perceived loudness and/or the perceived spectral balance of an audio signal
AssigneeDolby Laboratories Licensing Corporation
InventorAlan Jeffrey Seefeldt
Life of this patent
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Abstract
Audio signal processing relating to the measurement and control of the perceived sound loudness and/or the perceived spectral balance of an audio signal 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. In various embodiments, modification parameters are derived for modifying the audio signal in order to reduce the difference between its specific loudness and a target specific loudness.
Claims15
A method for controlling a particular loudness characteristic of an audio signal, wherein the particular loudness characteristic is either an approximation of specific loudness, which is a measure of perceptual loudness as a function of frequency and time, or an approximation of partial specific loudness, which is a measure of perceptual loudness of the signal in the presence of a secondary interfering signal as a function of frequency and time, comprising
- obtaining an approximation to a target specific loudness,
- deriving frequency-variant modification parameters usable for modifying the audio signal in order to reduce the difference between its particular loudness characteristic and said approximation to a target specific loudness, and
- a) applying the modification parameters to the audio signal to reduce the difference between its particular loudness characteristic and said approximation to a target specific loudness, or
- b) transmitting or storing the modification parameters and the audio signal for temporally separated, spatially separated, or both temporally separated and spatially separated application of the modification parameters to the audio signal to reduce the difference between its particular loudness characteristic and said approximation to a target specific loudness.
A method for controlling a particular loudness characteristic of an audio signal, wherein the particular loudness characteristic is either an approximation of specific loudness, which is a measure of perceptual loudness as a function of frequency and time, or an approximation of partial specific loudness, which is a measure of perceptual loudness of the audio signal in the presence of a secondary interfering signal as a function of frequency and time, comprising
- receiving from a transmission or reproducing from a storage medium the audio signal and
- a) frequency-variant modification parameters for modifying the audio signal, the modification parameters having been derived from an approximation to a target specific loudness, or
- b) an approximation to a target specific loudness or a representation of the approximation to that target specific loudness, and
- modifying the audio signal in response to a) the received modification parameters or b) modification parameters derived from said approximation to a target specific loudness or its representation in order to reduce the difference between the particular loudness characteristic of the audio signal and said approximation to a target specific loudness.
Dependencies are inferred from the claim text.