Techniques for dynamically managing a low-frequency sound field using non-low-frequency loudspeakers
View Patent ↗Disclosed embodiments include techniques for generating a low-frequency sound field for an audio system. A computing device in the audio system determines that a first playback level of an audio input is less than a maximum playback level of the audio system. Based on the first playback level, the computing device retrieves one or more first parameters associated with a first loudspeaker included in the audio system, where the one or more first parameters decrease a first cutoff frequency of the first loudspeaker to a second cutoff frequency. The computing device modifies a first portion of an audio signal transmitted to the first loudspeaker to decrease the first cutoff frequency to the second cutoff frequency based on the one or more first parameters.
1 . A computer-implemented method for generating a low-frequency sound field for an audio system, the method comprising:
determining that a first playback level of a low-frequency portion of an audio input is less than a maximum playback level of a first loudspeaker of the audio system;
determining, based on the first playback level, an extended cutoff frequency for the first loudspeaker;
retrieving one or more first parameters associated with the first loudspeaker included in the audio system;
splitting a coherent portion of the audio input from a non-coherent portion of the audio input; and
extending a frequency range of the first loudspeaker to the extended cutoff frequency by modifying, based on the one or more first parameters, the coherent portion of an audio signal transmitted to the first loudspeaker to increase output at frequencies below a first cutoff frequency of the first loudspeaker by an amount equivalent to a difference between a nominal operating curve and a reduced operating curve of the first loudspeaker.
2 . The computer-implemented method of claim 1 , wherein the one or more first parameters include at least one of a gain parameter, a delay parameter, or a filter parameter associated with the first loudspeaker.
3 . The computer-implemented method of claim 1 , further comprising selecting an entry in a lookup table that includes the one or more first parameters based on the first playback level of the audio input.
4 . The computer-implemented method of claim 1 , wherein modifying the coherent portion of the audio signal based on the one or more first parameters comprises applying a shelving filter to amplify frequencies that are lower than a second cutoff frequency.
5 . The computer-implemented method of claim 4 , further comprising:
determining that a second playback level of the audio input is different from the first playback level; and
based on the second playback level, retrieving one or more second parameters associated with the first loudspeaker included in the audio system, wherein the one or more second parameters change the second cutoff frequency of the first loudspeaker to a third cutoff frequency.
6 . The computer-implemented method of claim 5 , further comprising modifying a second portion of the audio signal based on the one or more second parameters by modifying a parameter of the shelving filter to amplify frequencies that are lower than the third cutoff frequency.
7 . The computer-implemented method of claim 1 , further comprising:
mixing the coherent portion of the audio signal with a second portion of the audio signal, wherein the second portion of the audio signal comprises frequencies above the first cutoff frequency.
8 . The computer-implemented method of claim 1 , further comprising determining the first playback level of the audio input based on playback levels of the audio input over a duration of time.
9 . The computer-implemented method of claim 1 , further comprising determining the first playback level of the audio input by:
mixing a first low frequency portion of a first audio input channel with a second low frequency portion of a second audio input channel to generate a mixer output; and
determining the first playback level of the audio input based on a playback level of the mixer output.
10 . The computer-implemented method of claim 1 , further comprising:
applying a lowpass filter to a first audio input channel to generate the audio input; and
applying a highpass filter to the first audio input channel to generate a mid/high frequency range audio output.
11 . The computer-implemented method of claim 1 , wherein the one or more first parameters determine a contribution of the first loudspeaker to the low-frequency sound field generated by the audio system.
12 . One or more non-transitory computer-readable media storing program instructions that, when executed by one or more processors, cause the one or more processors to perform steps of:
determining that a first playback level of a low-frequency portion of an audio input is less than a maximum playback level of a first loudspeaker of an audio system;
determining, based on the first playback level, an extended cutoff frequency for the first loudspeaker;
retrieving one or more first parameters associated with the first loudspeaker included in the audio system;
splitting a coherent portion of the audio input from a non-coherent portion of the audio input; and
extending a frequency range of the first loudspeaker to the extended cutoff frequency by modifying, based on the one or more first parameters, the coherent portion of an audio signal transmitted to the first loudspeaker to increase output at frequencies below a first cutoff frequency of the first loudspeaker by an amount equivalent to a difference between a nominal operating curve and a reduced operating curve of the first loudspeaker.
13 . The one or more non-transitory computer-readable media of claim 12 , wherein the one or more first parameters include at least one of a gain parameter, a delay parameter, or a filter parameter associated with the first loudspeaker.
14 . The one or more non-transitory computer-readable media of claim 12 , wherein the steps further comprise selecting an entry in a lookup table that includes the one or more first parameters based on the first playback level of the audio input.
15 . The one or more non-transitory computer-readable media of claim 12 , wherein modifying the coherent portion of the audio signal based on the one or more first parameters comprises applying a shelving filter to amplify frequencies that are lower than a second cutoff frequency.
16 . The one or more non-transitory computer-readable media of claim 12 , wherein the one or more first parameters determine a contribution of the first loudspeaker to a low-frequency sound field generated by the audio system.
17 . An audio system, comprising:
a first loudspeaker;
one or more memories storing instructions; and
one or more processors coupled to the one or more memories and, when executing the instructions:
determine that a first playback level of a low-frequency portion of an audio input is less than a maximum playback level of the first loudspeaker of the audio system;
determine, based on the first playback level, an extended cutoff frequency for the first loudspeaker;
retrieve one or more parameters associated with the first loudspeaker included in the audio system;
splitting a coherent portion of the audio input from a non-coherent portion of the audio input; and
extend a frequency range of the first loudspeaker to the extended cutoff frequency by modifying, based on the one or more parameters, the coherent portion of an audio signal transmitted to the first loudspeaker to increase output at frequencies below a first cutoff frequency of the first loudspeaker by an amount equivalent to a difference between a nominal operating curve and a reduced operating curve of the first loudspeaker.
18 . The audio system of claim 17 , wherein the audio system further comprises a mixer, wherein the mixer is configured mix the coherent portion of the audio signal with a second portion of the audio signal, wherein the second portion of the audio signal comprises frequencies above the first cutoff frequency.
19 . The audio system of claim 17 , wherein the one or more memories further stores a lookup table, and further comprising selecting an entry in the lookup table that includes the one or more parameters based on the first playback level of the audio input.
20 . The audio system of claim 17 , further comprising a shelving filter, wherein the shelving filter is configured based on the one or more parameters to modify the coherent portion of the audio signal by amplifying frequencies that are lower than a second cutoff frequency.