Methods and systems for audio signal filtering
Systems and methods for rendering audio signals are disclosed. In some embodiments, a method may receive an input signal including a first portion and the second portion. A first processing stage comprising a first filter is applied to the first portion to generate a first filtered signal. A second processing stage comprising a second filter is applied to the first portion to generate a second filtered signal. A third processing stage comprising a third filter is applied to the second portion to generate a third filtered signal. A fourth processing stage comprising a fourth filter is applied to the second portion to generate a fourth filtered signal. A first output signal is determined based on a sum of the first filtered signal and the third filtered signal. A second output signal is determined based on a sum of the second filtered signal and the fourth filtered signal. The first output signal is presented to a first ear of a user of a virtual environment, and the second output signal is presented to the second ear of the user. The first portion of the input signal corresponds to a first location in the virtual environment, and the second portion of the input signal corresponds to a second location in the virtual environment.
1. A method comprising:
receiving, at an amplitude panning stage, an audio input signal;
processing the audio input signal to generate a first processed signal and a second processed signal, wherein the processing comprises:
applying a first filter to the audio input signal,
aligning the first filter and a second filter, and
applying the second filter to the audio input signal;
adjusting, with respect to a first virtual speaker, a gain of the first processed signal to generate a first virtual speaker output;
adjusting, with respect to a second virtual speaker, based on the gain of the first processed signal, a gain of the second processed signal to generate a second virtual speaker output;
determining, based on a sum of the first virtual speaker output and the second virtual speaker output, a virtual speaker array output associated with a virtual speaker array comprising the first virtual speaker and the second virtual speaker; and
presenting the virtual speaker array output to one or more of a first speaker and a second speaker,
wherein the first speaker and the second speaker are associated with a wearable head device.
2. The method of claim 1 , wherein said aligning the first filter and the second filter comprises determining an inter-filter delay (IFD) and applying the IFD to one of the first filter and the second filter.
3. The method of claim 2 , further comprising modifying the IFD based on an anthropometric feature of a user of the wearable head device.
4. The method of claim 2 , further comprising adjusting the IFD based on an output of a sensor of the wearable head device.
5. The method of claim 1 , wherein said aligning the first filter and the second filter comprises:
determining a transfer function associated with the virtual speaker array; and
selecting an alignment based on the transfer function to minimize an amount of distortion.
6. The method of claim 5 , wherein said determining a transfer function associated with the virtual speaker array comprises empirically measuring the transfer function.
7. The method of claim 1 , wherein said aligning the first filter and the second filter comprises:
applying an audio signal to the virtual speaker array;
detecting a timbral artifact associated with the application of the audio signal to the virtual speaker array; and
selecting an alignment to reduce the timbral artifact.
8. A system comprising:
a wearable head device including a first speaker and a second speaker; and
one or more processors configured to perform a method comprising:
receiving, at an amplitude panning stage, an audio input signal;
processing the audio input signal to generate a first processed signal and a second processed signal, wherein the processing comprises:
applying a first filter to the audio input signal,
aligning the first filter and a second filter, and
applying the second filter to the audio input signal;
adjusting, with respect to a first virtual speaker, a gain of the first processed signal to generate a first virtual speaker output;
adjusting, with respect to a second virtual speaker, based on the gain of the first processed signal, a gain of the second processed signal to generate a second virtual speaker output;
determining, based on a sum of the first virtual speaker output and the second virtual speaker output, a virtual speaker array output associated with a virtual speaker array comprising the first virtual speaker and the second virtual speaker; and
presenting the virtual speaker array output to one or more of the first speaker and the second speaker.
9. The system of claim 8 , wherein said aligning the first filter and the second filter comprises determining an IFD and applying the IFD to one of the first filter and the second filter.
10. The system of claim 9 , wherein the method further comprises modifying the IFD based on an anthropometric feature of a user of the wearable head device.
11. The system of claim 9 , wherein:
the wearable head device comprises one or more sensors; and
the method further comprises adjusting the IFD based on an output of the one or more sensors.
12. The system of claim 8 , wherein said aligning the first filter and the second filter comprises:
determining a transfer function associated with the virtual speaker array; and
selecting an alignment based on the transfer function to minimize an amount of distortion.
13. The system of claim 12 , wherein said determining a transfer function associated with the virtual speaker array comprises empirically measuring the transfer function.
14. The system of claim 8 , wherein said aligning the first filter and the second filter comprises:
applying an audio signal to the virtual speaker array;
detecting a timbral artifact associated with the application of the audio signal to the virtual speaker array; and
selecting an alignment to reduce the timbral artifact.
15. A non-transitory computer-readable medium storing instructions which, when executed by one or more processors, cause the one or more processors to perform a method comprising:
receiving, at an amplitude panning stage, an audio input signal;
processing the audio input signal to generate a first processed signal and a second processed signal, wherein the processing comprises:
applying a first filter to the audio input signal,
aligning the first filter and a second filter, and
applying the second filter to the audio input signal;
adjusting, with respect to a first virtual speaker, a gain of the first processed signal to generate a first virtual speaker output;
adjusting, with respect to a second virtual speaker, based on the gain of the first processed signal, a gain of the second processed signal to generate a second virtual speaker output;
determining, based on a sum of the first virtual speaker output and the second virtual speaker output, a virtual speaker array output associated with a virtual speaker array comprising the first virtual speaker and the second virtual speaker; and
presenting the virtual speaker array output to one or more of a first speaker and a second speaker,
wherein the first speaker and the second speaker are associated with a wearable head device.
16. The non-transitory computer-readable medium of claim 15 , wherein said aligning the first filter and the second filter comprises determining an IFD and applying the IFD to one of the first filter and the second filter.
17. The non-transitory computer-readable medium of claim 16 , wherein the method further comprises modifying the IFD based on an anthropometric feature of a user of the wearable head device.
18. The non-transitory computer-readable medium of claim 16 , wherein the method further comprises adjusting the IFD based on an output of a sensor of the wearable head device.
19. The non-transitory computer-readable medium of claim 15 , wherein said aligning the first filter and the second filter comprises:
determining a transfer function associated with the virtual speaker array; and
selecting an alignment based on the transfer function to minimize an amount of distortion.
20. The non-transitory computer-readable medium of claim 15 , wherein said aligning the first filter and the second filter comprises:
applying an audio signal to the virtual speaker array;
detecting a timbral artifact associated with the application of the audio signal to the virtual speaker array; and
selecting an alignment to reduce the timbral artifact.