Positional audio rendering

• US 6,839,438 B1
• Filed: 08/02/2000
• Issued: 01/04/2005
• Est. Priority Date: 08/31/1999
• Status: Expired due to Term

• Current Assignee: Creative Technology Ltd.
• Original Assignee: Creative Technology Ltd.
• Inventors: Walsh, Martin, Riegelsberger, Edward
• Primary Examiner(s): Harvey, Minsun Oh
• Application Number:
  US09/630,439
• Time in Patent Office: 1,616 Days
• Field of Search: 381/18, 381/17, 381/303, 381/1
• US Class Current: 381/18
• 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

Abstract

An audio rendering system and method are disclosed. The audio rendering system generally comprises front and rear signal modifiers configured to receive a plurality of audio signals representing a plurality of sources of aural information and location information representing apparent location for the source of said aural information. A gain is applied to the signals representative of the location information. A front signal modifier includes a plurality of head-related transfer functions filters and a rear signal modifier includes a plurality of filters configured to approximate head-related transfer function filters. The system further includes front speakers comprising a left front speaker and right front speaker configured to receive signals from the front signal modifier and generate a signal to a listener. At least one rear speaker is configured to receive signals from the rear signal modifier and generate a signal to the listener to offset frontward bias created by the front speakers. The gains applied to the signal are calculated to produce generally equal perceived energy from each of the front and rear speakers.

Claims

1. An audio rendering system comprising:

a front signal modifier configured to receive a plurality of audio signals representing a plurality of sources of aural information and location information representing apparent locations for the sources of said aural information, and apply a gain to the signals representative of the location information, the front signal modifier including a plurality of head-related transfer function filters;

a rear signal modifier configured to receive the plurality of audio signals representing a plurality of sources of aural information and location information representing apparent locations for the sources of said aural information, in the same unmodified form in which they are received at the front signal modifier, and apply a gain to the signals representative of the location information, the rear signal modifier including a plurality of panning filters configured to approximate head-related transfer function filters;

front speakers including a left front speaker and a right front speaker configured to receive signals from the front signal modifier and generate a signal to a listener; and

at least one rear speaker configured to receive signals from the rear signal modifier and generate a signal to the listener to offset frontward bias created by the front speakers;

whereby the gains applied to the signal are calculated to produce generally equal perceived energy from each of the front and rear speakers.

2. The audio rendering system of claim 1 wherein the front signal modifier includes a mixer operable to combine the signals to provide a signal to the front left speaker and the front right speaker.

3. The audio rendering system of claim 2 further comprising a cross-talk canceller interposed between the mixer and the front left and right speakers.

4. The audio rendering system of claim 1 wherein the rear signal modifier includes a mixer.

5. The audio rendering system of claim 1 wherein the front and rear signal modifiers each include a cross-talk canceller.

6. The audio rendering system of claim 1 further comprising a second rear speaker.

7. A method for providing a two channel signal to the ears of a listener through an audio system including a plurality of audio signals which are played through two front speakers and at least one rear speaker, comprising:

receiving a plurality of audio signals representing a plurality of sound sources; and

generating front input signals by applying a head related transfer function to each signal representative of a location of each of the sound sources;

applying a front gain to the front input signals to create front output signals and sending said front output signals to the two front speakers;

filtering the plurality of audio signals in their original unmodified form using a plurality of panning filters to generate rear input signals that provide left and right panning between the two rear speakers; and

applying a rear gain to the rear input signals to create rear output signals and sending said rear output signals to the rear speaker;

whereby the gains applied to the signals are calculated to produce generally equal perceived energy from each of the front and rear speakers.

8. The method of claim 7 further comprising canceling cross-talk in said front speakers.

9. The method of claim 7 further comprising sending the rear signals to two rear speakers.