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US 11,109,155 B2Granted
Bass enhancement
AssigneeCirrus Logic, Inc.
InventorEric Lindemann
Life of this patent
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Abstract
A bass enhancement may be applied to improve the perception of low-frequency sounds by a user of an electronic device. A distortion function may be applied to the audio signal that results in creation of higher frequency content related to the low-frequency sounds. This higher frequency content may be interpreted by a listener's ear in a similar manner as the low-frequency sounds. The distortion function may be a Sigmoid function. Bass enhancements may also include scaling of the audio signal prior to distortion, adaptation of the distortion, or gap band filtering prior to the distortion.
Claims20
A method, comprising:
- receiving an input audio signal;
- generating a first audio signal from the input audio signal;
- applying a low-pass filter to the input audio signal to generate a second audio signal;
- processing the second audio signal to form a processed second audio signal of the input audio signal, wherein the processing comprises the steps of:
- applying a non-linear distortion to at least a portion of a frequency spectrum of the second audio signal to obtain a distorted second audio signal, wherein the processed second audio signal is based, at least in part, on the distorted second audio signal, wherein applying the non-linear distortion produces a series of harmonics as a high-frequency distortion band comprising integer multiples of a fundamental frequency, the fundamental frequency being in a low-frequency band of the input audio signal below a high-frequency cut-off of the low-pass filter;
- and
- adjusting parameters for the non-linear distortion applied to the second audio signal based, at least in part, on the processed second audio signal to maintain a relationship of a measure of intensity in a high-frequency distortion band of the non-linear distortion to a measure of intensity in the low-frequency band;
- and
- combining the processed second audio signal with the first audio signal to produce an output audio signal.
6 more elements
An apparatus, comprising:
- an audio controller configured to perform steps comprising:
- processing a second audio signal to form a processed second audio signal, wherein the second audio signal comprises low-frequency content of an original audio signal, and wherein the processing comprises the steps comprising:
- applying a non-linear distortion to at least a portion of a frequency spectrum of a second audio signal to obtain a distorted second audio signal wherein the second audio signal comprises low-frequency content of an original audio signal, wherein the non-linear distortion produces a series of harmonics as a high-frequency distortion band comprising integer multiples of a fundamental frequency, the fundamental frequency being in a low-frequency band of the input audio signal below a high-frequency cut-off of the low-pass filter;
- and
- adjusting parameters for the non-linear distortion applied to the second audio signal based, at least in part, on the processed second audio signal to maintain a relationship of a measure of intensity in a high-frequency distortion band of the non-linear distortion to a measure of intensity in the low-frequency band;
- combining the processed second audio signal with a first audio signal to produce an output audio signal, wherein the first audio signal comprises the original audio content without the low-frequency content.
3 more elements
An apparatus, comprising:
- an input node configured to receive an input audio signal;
- a gap band filter coupled to the input node and configured to generate a first audio signal without low-frequency content and to generate a second audio signal with low-frequency content;
- a bass processing block configured to receive the second audio signal and to generate a processed second audio signal from the second audio signal, the bass processing block comprising:
- a dynamic range compression block configured to scale the second audio signal to obtain a scaled second audio signal;
- a non-linear distortion block configured to apply a non-linear distortion to the scaled second audio signal to obtain a distorted second audio signal, wherein the non-linear distortion produces a series of harmonics as a high-frequency distortion band comprising integer multiples of a fundamental frequency, the fundamental frequency being in a low-frequency band of the input audio signal below a high-frequency cut-off of the second audio signal;
- a dynamic range expansion block configured to scale the distorted second audio signal to obtain a scaled distorted second audio signal, wherein the processed second audio signal is based, at least in part, on the scaled distorted second audio signal;
- and
- a distortion adjustment block configured to adjust parameters for the non-linear distortion applied to the second audio signal based, at least in part, on the processed second audio signal to maintain a relationship of a measure of intensity in a high-frequency distortion band of the non-linear distortion to a measure of intensity in the low-frequency band;
- and
- a combiner coupled to the bass processing block to receive the processed second audio signal and coupled to the gap band filter to receive the first audio signal.
7 more elements
Dependencies are inferred from the claim text.