Systems and methods of adjusting bass levels of multi-channel audio signals

Patent metadata

Field	Value
Publication number	US-12170885-B2
Application number	US-202318332387-A
Country	US
Kind code	B2
Filing date	Jun 9, 2023
Priority date	Mar 21, 2018
Publication date	Dec 17, 2024
Grant date	Dec 17, 2024

Abstract

Systems and methods for adjusting bass levels of a multi-channel audio signal include, among other features, (i) receiving the multi-channel signal via a playback device; (ii) separating, from the multi-channel signal, low-frequency signals comprising frequencies less than a threshold frequency; (iii) determining electrical energies of the low-frequency signals; (iv) determining a first energy by summing the electrical energies of the low-frequency signals; (v) consolidating the low-frequency signals into a consolidated low-frequency signal; (vi) determining a second energy by determining an electrical energy of the consolidated low-frequency signal; (vii) generating a gain-adjusted low-frequency signal by adjusting a gain of the consolidated low-frequency signal based on both (a) the first energy and (b) the second energy; (viii) generating a gain-adjusted multi-channel signal by mixing the gain-adjusted low-frequency signal back into the multi-channel signal; and (ix) using the gain-adjusted multi-channel signal to play back gain-adjusted multi-channel audio content via the playback device.

First claim

What is claimed is:

1. A system comprising:
one or more processors;
tangible, non-transitory computer-readable media comprising program instructions executable by the one or more processors such that the system is configured to:
receive a multi-channel audio signal comprising a first channel and a second channel;
for the first channel, (i) apply a low pass filter to the first channel to obtain a low-frequency component of the first channel, wherein the low-frequency component of the first channel comprises audio information below a threshold frequency, and (ii) determine an energy of the low-frequency component of the first channel;
for the second channel, (i) apply the low pass filter to the second channel to obtain a low-frequency component of the second channel, wherein the low-frequency component of the second channel comprises audio information below the threshold frequency, and (ii) determine an energy of the low-frequency component of the second channel;
sum the energies of the determined low-frequency components to obtain a sum of energies of the low-frequency components;
combine the determined low-frequency components of each channel into a consolidated low-frequency signal;
determine an electrical energy of the consolidated low-frequency signal;
generate a gain-adjusted low-frequency signal based on (i) the sum of the energies of the low-frequency components and (ii) the electrical energy of the consolidated low-frequency signal;
generate a gain-adjusted multi-channel audio signal comprising the gain-adjusted low-frequency signal; and
cause playback of the gain-adjusted multi-channel audio signal via a plurality of audio drivers.

2. The system of claim 1 , wherein the first channel comprises a left channel and the second channel comprises a right channel.

3. The system of claim 1 , wherein the multi-channel audio signal further comprises a third channel, and wherein the program instructions further comprise program instructions executable by the one or more processors such that the system is configured to:
for the third channel, (i) apply a low pass filter to the third channel to obtain a low-frequency component of the third channel, wherein the low-frequency component of the third channel comprises audio information below a threshold frequency, and (ii) determine an energy of the low-frequency component of the third channel.

4. The system of claim 1 , wherein the program instructions executable by the one or more processors such that the system is configured to generate the gain-adjusted low-frequency signal based on (i) the sum of the energies of the low-frequency components and (ii) the electrical energy of the consolidated low-frequency signal comprise program instructions executable by the one or more processors such that the system is configured to:
calculate a gain according to G=E 1 /E 2 , where G comprises the gain, E 1 comprises the sum of the energies of the low-frequency components, and E 2 comprises the electrical energy of the consolidated low-frequency signal; and
generate the gain-adjusted low-frequency signal by applying the gain to the consolidated low-frequency signal.

5. The system of claim 1 , wherein the program instructions executable by the one or more processors such that the system is configured to generate the gain-adjusted low-frequency signal based on (i) the sum of the energies of the low-frequency components and (ii) the electrical energy of the consolidated low-frequency signal comprise program instructions executable by the one or more processors such that the system is configured to:
calculate a gain according to G=[E 1 +(Γ*ε)]/[E 2 +ε], where G comprises the gain, E 1 comprises the sum of the energies of the low-frequency components, E 2 comprises the electrical energy of the consolidated low-frequency signal, Γ comprises a default gain, and ε comprises a constant; and
generate the gain-adjusted low-frequency signal by applying the gain to the consolidated low-frequency signal.

6. The system of claim 1 , wherein the program instructions executable by the one or more processors such that the system is configured to generate the gain-adjusted multi-channel audio signal comprising the gain-adjusted low-frequency signal comprise program instructions executable by the one or more processors such that the system is configured to:
for the first channel, (i) apply a high pass filter to the first channel to obtain a high-frequency component of the first channel, wherein the high-frequency component of the first channel comprises audio information above the threshold frequency, and (ii) mix the high-frequency component of the first channel with the gain-adjusted low-frequency signal; and
for the second channel, (i) apply the high pass filter to the second channel to obtain a high-frequency component of the second channel, wherein the high-frequency component of the second channel comprises audio information above the threshold frequency, and (ii) mix the high-frequency component of the second channel with the gain-adjusted low-frequency signal.

7. The system of claim 1 , wherein each channel in the multi-channel audio signal corresponds to a sound axis, and wherein the program instructions executable by the one or more processors such that the system is configured to cause playback of the gain-adjusted multi-channel audio signal via the plurality of audio drivers comprise program instructions executable by the one or more processors such that the system is configured to:
for each gain-adjusted channel in the gain-adjusted multi-channel audio signal, cause playback of the gain-adjusted channel via a sound axis corresponding to the channel.

8. The system of claim 7 , further comprising the plurality of audio drivers, wherein the plurality of audio drivers comprises a first audio driver and a second audio driver, and wherein a value of the threshold frequency is based at least in part on a distance between the first audio driver and the second audio driver.

9. The system of claim 8 , wherein the distance between the first audio driver and the second audio driver is an odd-integer multiple of a quarter-wavelength of the threshold frequency.

10. The system of claim 1 , wherein the one or more processors, the tangible, non-transitory computer-readable media, and the plurality of audio drivers are contained within a single playback device.

11. Tangible, non-transitory computer-readable media comprising program instructions executable by one or more processors such that a system is configured to perform functions comprising:
receiving a multi-channel audio signal comprising as first channel and a second channel;
for the first channel, (i) applying a low pass filter to the first channel to obtain a low-frequency component of the first channel, wherein the low-frequency component of the first channel comprises audio information below a threshold frequency, and (ii) determining an energy of the low-frequency component of the first channel;
for the second channel, (i) applying the low pass filter to the second channel to obtain a low-frequency component of the second channel, wherein the low-frequency component of the second channel comprises audio information below the threshold frequency, and (ii) determining an energy of the low-frequency component of the second channel;
summing the energies of the determined low-frequency components to obtain a sum of energies of the low-frequency components;
combining the determined low-frequency components of each channel into a consolidated low-frequency signal;
determining an electrical energy of the consolidated low-frequency signal;
generating a gain-adjusted low-frequency signal based on (i) the sum of

Assignees

• Sonos Inc

Inventors

• Lehnert Hilmar
• Ramos Aurelio
• Dizon Bob

Classifications

• H04S2400/07

  Generation or adaptation of the Low Frequency Effect [LFE] channel, e.g. distribution or signal processing · CPC title

• H04S3/002

  Non-adaptive circuits, e.g. manually adjustable or static, for enhancing the sound image or the spatial distribution (control circuits for electronic adaptation of the sound field H04S7/30) · CPC title

• H04S3/006

  in which a plurality of audio signals are transformed in a combination of audio signals and modulated signals, e.g. CD-4 systems · CPC title

• H04S2400/01

  Multi-channel, i.e. more than two input channels, sound reproduction with two speakers wherein the multi-channel information is substantially preserved · CPC title

• G10L21/0272

  Voice signal separating · CPC title