Multi-channel audio enhancement system for use in recording playback and methods for providing same

• US 7,200,236 B1
• Filed: 02/24/1999
• Issued: 04/03/2007
• Est. Priority Date: 11/07/1996
• Status: Expired due to Fees

• Current Assignee: DTS, Inc. (Adeia Inc.)
• Original Assignee: Srslabs Incorporated
• Inventors: Kraemer, Alan D., Klayman, Arnold I.
• Primary Examiner(s): Mei; Xu
• Application Number:
  US09/256,982
• Time in Patent Office: 2,960 Days
• Field of Search: 381/1, 381/22, 381/21, 381/23, 381/17, 381/18, 381/19, 381/20
• US Class Current: 381/18
• 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 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 3/008 in which the audio signals are in digital form, i.e. employing more than two discrete digital channels data reduction aspects thereof based on psychoacoustics G10L19/02

Abstract

An audio enhancement system and method for use receives a group of multi-channel audio signals and provides a simulated surround sound environment through playback of only two output signals. The multi-channel audio signals comprise a pair of front signals intended for playback from a forward sound stage and a pair of rear signals intended for playback from a rear sound stage. The front and rear signals are modified in pairs by separating an ambient component of each pair of signals from a direct component and processing at least some of the components with a head-related transfer function. Processing of the individual audio signal components is determined by an intended playback position of the corresponding original audio signals. The individual audio signal components are then selectively combined with the original audio signals to form two enhanced output signals for generating a surround sound experience upon playback.

Claims

1. A method of processing a plurality of audio source signals to create a pair of audio output signals, the method comprising:

combining a first and a second audio source signal to form a first pair of audio source signals;

enhancing the first pair of audio source signals;

combining a third and a fourth audio source signal to form a second pair of audio source signals;

enhancing the second pair of audio source signals;

combining the first audio source signal with at least portions of the first and second enhanced pairs of audio source signals to generate a first output signal; and

combining the second audio source signal with at least portions of the first and second enhanced pairs of audio source to generate a second output signal.

2. The method of claim 1 wherein combining to form the first pair of audio source signals forms an ambient component and a monophonic component.

3. The method of claim 1 wherein combining to form the second pair of audio source signals forms an ambient component and a monophonic component.

4. The method of claim 1 wherein combining to form the first output signal further comprises combining the third audio source signal.

5. The method of claim 1 wherein combining to form the second output signal further comprises combining the fourth audio source signal.

6. A method of processing five audio source signals to create a pair of audio output signals, the method comprising:

combining a left front input signal and a right front input signal to create a first pair of signals;

processing the first pair of signals;

combining a left rear input signal and a right rear input signal to create a second pair of signals;

processing the second pair of signals;

combining the left front input signal with at least portions of the first and second pairs of processed signals and with at least portions of a center signal to generate a first output signal; and

combining the right front input signal with at least portions of the first and second pairs of processed signals and with at least portions of the center signal to generate a second output signal.

7. The method of claim 6 wherein the first output signal further comprises the left rear input signal.

8. The method of claim 6 wherein the second output signal further comprises the right rear input signal.

9. A method of processing five audio source signals to create a pair of audio output signals, the method comprising:

combining a left front input signal and a right front input signal to create a first pair of signals;

processing the first pair of signals;

combining a left rear input signal and a right rear input signal to create a second pair of signals;

processing the second pair of signals;

combining the left front input signal with at least portions of the first and second pairs of processed signals and with at least portions of a center signal to generate a first output signal; and

combining the right front input signal with at least portions of the first and second pairs of processed signals and with at least portions of the center signal to generate a second output signal, wherein enhancing the first pair of audio source signals comprises applying a frequency response curve to the first pair of audio source signals, wherein a gain of the frequency response curve has a peak gain at approximately 125 Hz and the gain decreases above and below approximately 125 Hz at a rate of approximately 6 dB per octave, and wherein the gain of the frequency response curve has a minimum gain at frequencies between approximately 1.5 kHz to approximately 2.5 kHz and the gain increases above frequencies between approximately 1.5 kHz to approximately 2.5 kHz at a rate of approximately 6 dB per octave up to approximately 7 kHz and continues to increase up to approximately 20 kHz.

10. The method of claim 9 wherein a gain separation between the peak gain and the minimum gain is approximately 9 dB and the gain separation between the minimum gain and the gain at approximately 7 kHz is approximately 6 dB.

11. A method of processing five audio source signals to create a pair of audio output signals, the method comprising:

combining a left front input signal and a right front input signal to create a first pair of signals;

processing the first pair of signals;

combining a left rear input signal and a right rear input signal to create a second pair of signals;

processing the second pair of signals;

combining the left front input signal with at least portions of the first and second pairs of processed signals and with at least portions of a center signal to generate a first output signal; and

combining the right front input signal with at least portions of the first and second pairs of processed signals and with at least portions of the center signal to generate a second output signal, wherein enhancing the second pair of audio source signals comprises applying a frequency response curve to the second pair of audio source signals, wherein a gain of the frequency response curve has a peak gain at approximately 125 Hz and the gain decreases above and below approximately 125 Hz at a rate of approximately 6 dB per octave, and wherein the gain of the frequency response curve has a minimum gain between approximately 1.5 kHz to approximately 2.5 kHz and the gain increases at frequencies above approximately 1.5 kHz to approximately 2.5 kHz at a rate of approximately 6 dB per octave up to frequencies between approximately 10.5 kHz to approximately 11.5 kHz and decreases at frequencies between approximately 11.5 kHz to approximately 20 kHz.

12. The method of claim 11 wherein a gain separation between the peak gain and the minimum gain is approximately 18 dB and the gain separation between the minimum gain and the gain between approximately 10.5 kHz to approximately 11.5 kHz is approximately 10 dB.