Electrical audio signal processing systems and devices – Binaural and stereophonic – Stereo speaker arrangement
Reexamination Certificate
1997-07-11
2001-07-10
Isen, Forester W. (Department: 2644)
Electrical audio signal processing systems and devices
Binaural and stereophonic
Stereo speaker arrangement
C381S311000, C381S018000
Reexamination Certificate
active
06259795
ABSTRACT:
FIELD OF THE INVENTION
The present invention relates to the field of audio processing and in particular, to the creation of an audio environment for multiple users wherein it is designed to give each user an illusion of sound (or sounds) located in space.
BACKGROUND OF THE INVENTION
U.S. Pat. No. 3,962,543 by Blauert et. al discloses a single user system to locate a mono sound input at a predetermined location in space. The Blauert et. al. specification applies to individual monophonic sound signals only and does not include any reverberation response and hence, although it may be possible to locate a sound at a radial position, due to the lack of reverberation response, no sound field is provided and no perception of distance of a sound object is possible. Further, it is doubtful that the Blauert et. al. disclosure could be adapted to a multi-user environment and in any event does not disclose the utilisation of sound field signals in a multi-user environment but rather one or more monophonic sound signals only.
U.S. Pat. No. 5,596,644 by Abel et al. describes a way of presenting a 3D sound to a listener by using a discrete set of filters with pre-mixing or post-mixing of the filter inputs or outputs so as to achieve arbitrary location of sounds around a listener. The patent relies on a break-down of the Head Related Transfer Functions (HRTFs) of a typical listener, into a number of main components (using the well known technique of Principal Component Analysis). Any single sound event may be made to appear to come from any direction by filtering it through these component filters and then summing the filters together, with the weighing of each filter being varied to provide an overall summed response that approximates the desired HRTF. Abel et. al. does not allow for the input to be represented as a soundfield with full spatial information pre-encoded (rather than as a collection of single, dry, sources) and to manipulate the mixing of the filters before or after the filters to simulate headtracking. Neither of these benefits are obtained by the Abel et. al.
Thus, there is a general need for a simple system for the creation of an audio environment for multiple users wherein it is designed to give each user an illusion of sound (or sounds) located in space.
SUMMARY OF THE INVENTION
It is an object of the present invention to provide for an efficient and effective method of transmission of sound field signals to multiple users.
In accordance with the first aspect of the present invention there is provided a method for distribution to multiple users of a soundfield having positional spatial components, said method comprising the steps of:
inputting a soundfield signal having the desired positional spatial components in a standard reference frame;
applying at least one head related transfer function to each spatial component to produce a series of transmission signals;
transmitting said transmission signals to said multiple users;
for each of said multiple users:
determining a current orientation of a current user and producing a current orientation signal indicative thereof;
utilising said current orientation signal to mix said transmission signals so as to produce sound emission source output signals for playback to said user.
Preferably, the soundfield signal includes a B-format signal and said applying step comprises:
applying a head related transfer signal to the B-format X component signal said head related transfer signal being for a standard listener listening to the X component signal; and
applying a head related transfer signal to the B-format Y component signal said head related transfer signal being for a standard listener listening to the Y component signal;
Preferably, the output signals of said applying step can include the following:
XX : X input subjected to the finite impulse response for the head transfer function of X
XY: X input subjected to the finite impulse response for the head transfer function of Y;
YY: Y input subjected to the finite impulse response for the head transfer function of Y;
YX: Y input subjected to the finite impulse response for the head transfer function of X;
The mix can include producing differential and common mode components signals from said transmission signals.
Preferably, applying step is extended to the Z component of the B-format signal.
In accordance with a third aspect of the present invention there is provided a method for reproducing sound for multiple listeners, each of said listeners able to substantially hear a first predetermined number of sound emission sources, said method comprising the steps of:
inputting a sound field signal;
determining a desired apparent source position of said sound information signal.
for each of said multiple listeners, determining a current position of corresponding said first predetermined number of sound emission sources; and
manipulating and outputting said sound information signal so that, for each of said multiple listeners, said sound information signal appears to be sourced at said desired apparent source position, independent of movement of said sound emission sources.
Preferably, the manipulating and outputting step further comprises the steps of:
determining a decoding function for a sound at said current source position for a second predetermined number of virtual sound emission sources;
determining a head transfer function from each of the virtual sound emission sources to each ear of a prospective listener;
combining said decoding functions and said head transfer functions to form a net transfer function for a second group of virtual sound emission sources when placed at predetermined positions to each ear of an expected listener of said second group of virtual sound emission sources;
applying said net transfer function to said sound information signal to produce a virtually positioned sound information signal;
for each of said multiple listeners, independently determining an activity mapping from said second group of virtual sound emission sources to said current source position of said sound information signal and applying said mapping to said sound information signal to produce said output.
In accordance with the fourth aspect of the present invention there is provided a sound format for utilisation in an apparatus for sound reproduction, including a direction component indicative of the direction from which a particular sound has come from, said directional component having been subjected to a head related transfer function.
In accordance with the fifth aspect of the present invention there is provided a sound format for utilisation in an apparatus for sound reproduction, said sound format created via the steps of:
determining a current sound source position for each sound to be reproduced;
applying a predetermined head transfer function to each of said sounds, said head transfer function being an expected mapping of said sound to each ear of a prospective listener when each ear has a predetermined orientation.
REFERENCES:
patent: 5583942 (1996-12-01), Va Den Berg
patent: 5757927 (1998-05-01), Gerzon et al.
patent: 5844816 (1998-12-01), Inanaga et al.
patent: 6021206 (2000-02-01), McGrath
Fulwider Patton Lee & Utecht
Isen Forester W.
Lake DSP Pty Ltd.
Pendleton Brian Tyrone
LandOfFree
Methods and apparatus for processing spatialized audio does not yet have a rating. At this time, there are no reviews or comments for this patent.
If you have personal experience with Methods and apparatus for processing spatialized audio, we encourage you to share that experience with our LandOfFree.com community. Your opinion is very important and Methods and apparatus for processing spatialized audio will most certainly appreciate the feedback.
Profile ID: LFUS-PAI-O-2458108