AUDIO SIGNAL PROCESSING

• US 20100226500A1
• Filed: 05/17/2010
• Published: 09/09/2010
• Est. Priority Date: 04/03/2006
• Status: Active Grant

• Current Assignee: DTS, Inc. (Adeia Inc.)
• Original Assignee: SRS Labs Incorporated (Adeia Inc.)
• Inventors: Wang, Wen
• Granted Patent: US 8,831,254 B2
• Time in Patent Office: Days
• US Class Current: 381/17
• CPC Class Codes: H04S 2400/01 Multi-channel, i.e. more than two input channels, sound reproduction with two speakers wherein the multi-channel information is substantially preserved
• CPC Class Codes: H04S 2400/05 Generation or adaptation of centre channel in multi-channel audio systems
• CPC Class Codes: H04S 2420/01 Enhancing the perception of the sound image or of the spatial distribution using head related transfer functions [HRTF's] or equivalents thereof, e.g. interaural time difference [ITD] or interaural level difference [ILD]
• CPC Class Codes: H04S 3/002 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 Class Codes: H04S 3/004 For headphones
• CPC Class Codes: H04S 3/02 of the matrix type, i.e. in which input signals are combined algebraically, e.g. after having been phase shifted with respect to each other
• CPC Class Codes: H04S 5/02 of the pseudo four-channel type, e.g. in which rear channel signals are derived from two-channel stereo signals

Abstract

Systems and methods of processing audio signals are described. The audio signals comprise information about spatial position of a sound source relative to a listener. At least one audio filter generates two filtered signals for each of audio signal. The two filtered signals are mixed with other filtered signals from other audio signals to create a right output audio channel and a left audio output channel, such that the spatial position of the sound source is perceptible from the right and left audio output channels.

Claims

1. A method of applying hearing response function approximations to audio signals to reduce spatial localization processing requirements, the method comprising:

receiving a first audio signal and a second audio signal;

filtering the first audio signal with one or more first positional filters, each of the one or more first positional filters configured to emphasize one or more first location-relevant portions of a head-related transfer function (HRTF) by at least applying two or more first component filters to the first audio signal to produce one or more first filtered signals;

filtering the second audio signal with one or more second positional filters, each of the one or more second positional filters configured to emphasize one or more second location-relevant portions of the HRTF by at least applying two or more second component filters to the second audio signal to produce one or more second filtered signals; and

combining the one or more first and second filtered signals to produce left and right output signals, such that spatial positions in the left and right output signals are perceptible from left and right speakers.

2. The method of claim 1, wherein said filtering the first audio signal with one or more first positional filters comprises filtering the first audio signal with two first positional filters and wherein said filtering the second audio signal with one or more second positional filters comprises filtering the second audio signal with two second positional filters.

3. The method of claim 2, wherein said combining the one or more first and second filtered signals comprises combining an output of one of the two first positional filters with an output of one of the two second positional filters to produce the left output signal.

4. The method of claim 2, wherein said combining the one or more first and second filtered signals comprises combining an output of one of the two first positional filters with an output of one of the two second positional filters to produce the right output signal.

5. The method of claim 1, wherein said filtering the first audio signal with one or more first positional filters comprises combining outputs of the two or more first component filters to at least partially produce the one or more first filtered signals.

6. The method of claim 1, further comprising filtering a third audio input signal with one or more third positional filters by applying two or more third component filters to at least partially produce a surround output signal.

7. A system for applying hearing response function approximations to audio signals to reduce spatial localization processing requirements, the system comprising:

one or more first positional filters implemented with one or more processors, each of the one or more first positional filters configured to emphasize one or more first location-relevant portions of a head-related transfer function (HRTF), the one or more first positional filters each comprising two or more first component filters configured to filter the first audio signal to produce one or more first filtered signals;

one or more second positional filters implemented with the one or more processors, each of the one or more second positional filters configured to emphasize one or more second location-relevant portions of a head-related transfer function (HRTF), the one or more second positional filters each comprising two or more second component filters configured to filter the second audio signal to produce one or more second filtered signals; and

a combiner configured to combine the one or more first and second filtered signals to produce left and right output signals, such that spatial positions in the left and right output signals are perceptible from left and right speakers.

8. The system of claim 7, wherein the one or more first positional filters are further configured to filter the first audio signal with two first positional filters and wherein the one or more second positional filters are further configured to filter the second audio signal with two second positional filters.

9. The system of claim 8, wherein the combiner is further configured to combine the one or more first and second filtered signals by at least combining an output of one of the two first positional filters with an output of one of the two second positional filters to produce the left output signal.

10. The system of claim 8, wherein the combiner is further configured to combine the one or more first and second filtered signals by at least combining an output of one of the two first positional filters with an output of one of the two second positional filters to produce the right output signal.

11. The system of claim 7, wherein the one or more first positional filters are further configured to filter the first audio signal by at least combining outputs of the two or more first component filters to at least partially produce the first filtered signal.

12. The system of claim 7, wherein the first component filters comprise a band stop filter, a band pass filter, and a high pass filter.

13. The system of claim 7, wherein the second component filters comprise a plurality of band stop filters.

14. The system of claim 7, wherein at least some of the first and second component filters are implemented as infinite impulse response (IIR) filters.