Abstract: An improved method and apparatus for creating multi-channel (or binaural) signals from a B-format sound-field source is disclosed. The method allows the encoded spatial format (B-format) to be separated into multiple bands, with each band assigned a short-term direction factor, from which the higher-resolution multi-channel (or binaural) output signals may be determined. The direction factor is determined, for each filter band, based on the short-term statistics of the soundfield signals in those bands. Based on this direction factor, the speaker drive signals are computed for each band by panning the signals to drive the nearest speakers. In addition, residual signal components are apportioned to the speaker signals by means of previously known decoding techniques.

Abstract: The invention provides a method and system for forming an output impulse response function. The method includes the steps of creating an initial impulse response, and dividing the impulse response into a head portion and a tail portion. The tail portion is high pass filtered, and low frequency components of the head portion are boosted. The low frequency boosted and high pass filtered respective head and tail portions are then combined into a modified output impulse response, which can then be used to spatialize an audio signal by convolving it.

Abstract: A convolution method and apparatus of time domain convolving an input signal with a second signal is disclosed comprising the steps of; dividing the second signal into a series of segments; determining a magnitude envelope for each of the segments; scaling the signal values within each segments relative to the envelope to produce corresponding segment scaled signal values; multiplying the segment scaled values by a corresponding input signal value to produce corresponding segment output values; scaling the segment output values by a segment scale factor to produce corresponding scaled segment outputs; and adding the scaled segment output to produce a time domain output.

Abstract: An audio system for providing an immersive audio experience, said system comprising: a recording system including a system for recording spatialised audio information at an event location; a broadcasting system for broadcasting said spatialised audio information to multiple users located away from said event location; and a plurality of rendering systems for rendering said broadcast spatialised audio information in a manner so as to create an apparent event location audio environment around each listener, wherein said spatialisation is maintained in the presence of movement of a listener's head.

Abstract: A method is dislcosed for stabilizing the apparent location of an audio signal having spatial components, in the presence of movement of emission sources designed to emit the audio signal while maintaining the apparent location, the method comprising the steps of (a) high pass filtering a signal proportional to the angular position of the emission sources; (b) utilizing the high pass filtered signal as an apparent angular position of the emission sources to determine an apparent location of the audio signal. Preferably, the high pass filtered signal is limited utilizing a non-linear asymptotically bounded function to limit the signal.

Abstract: A system for providing a listener with an augmented audio reality in a geographical environment said system comprising a position locating system for determining a current position and orientation of a listener in.

Abstract: A sigma delta modulator is disclosed and claimed. In one embodiment, the sigma delta modulator may comprise input means for inputting an input signal stream; summing means interconnect to the input means for adding a feedback signal stream to the input signal to produce an altered input signal stream; low pass filtering means interconnected to the summing means for low pass filtering the altered input signal stream to produce a low pass filtered signal stream; bit stuffing means for adding predetermined values in predetermined positions in the low pass filtered signal stream to form a bit stuffed low pass filtered stream; and a quantizer for quantizing the bit stuff low pass filtered signal to produce an output signal stream, the output signal stream also being fed back to the summing means so as to form the feedback signal stream.

Abstract: A computer system including a series of convolution libraries, a user interface, a convolver, and a filter.

Abstract: A convolution method and apparatus of time domain convolving an input signal with a second signal is disclosed comprising the steps of; dividing the second signal into a series of segments; determining a magnitude envelope for each of the segments; scaling the signal values within each segments relative to the envelope to produce corresponding segment scaled signal values; multiplying the segment scaled values by a corresponding input signal value to produce corresponding segment output values; scaling the segment output values by a segment scale factor to produce corresponding scaled segment outputs; and adding the scaled segment output to produce a time domain output.

Abstract: A method of performing a convolution of an input data stream, the method comprising the steps of: (a) transforming an initial series of input data values into the frequency domain to form initial frequency domain data values; (b) multiplying the frequency domain data values with a set of coefficients so as to form convolved frequency data; (c) transforming the convolved frequency data into a spatial domain so as to form an initial series of output data values; (d) performing steps (a) to (c) on a subsequent series of input data values of the input data stream so as to form a subsequent series of output data values; the subsequent series of input data values overlapping the initial series of input data values; and (e) cross fading overlapping portions of the initial and subsequent output data values.

Abstract: In a multi viewer environment where multiple viewers simultaneously experience an audio-visual production, with the visual production occurring on a display surface, a method of increasing the perceived reality of the audio stream of the production, the method comprising the steps of: (a) locating a series of speakers along a periphery of the viewing audience; (b) panning an audio stream between the series of speakers so as to provide for the sense of an audio sound moving along the side of the viewing audience. In preferred embodiments, the output of one of the speakers is delayed relative to another speaker.

Abstract: A sigma delta modulator apparatus comprising: input means for inputting a current input signal; differencing means for forming the difference between a current input signal and a current output signal; filtering means for filtering the difference so as to produce a filtered difference signal; and output means outputting a minimum or maximum output value so as to substantially minimize the filtered difference signal.

Abstract: An apparatus for implementing a Head Related Transfer Function on an input audio signal in a headtracked listening environment comprising: a series of principle component filters attached to the input audio signal and each outputting a predetermined simulated sound arrival; a series of delay elements each attached to a corresponding one of the principle component filters and delaying the output of the filter by a variable amount depending on a delay input so as to produce a filter delay output; a summation means interconnected to the series of delay elements and summing the filter delay outputs to produce an audio speaker output signal; headtrack parameter mapping unit having a current orientation signal input and interconnected to each of the series of delay elements so as to provided the delay inputs.

Abstract: An improved method and apparatus for recreating spatially natural soundfields in a variety of listening environments is disclosed. The apparatus includes a speaker cabinet that contains multiple drivers each driven so as to effect an overall radiation pattern that mimics the soundfield pattern described by a B-format signal vector. This apparatus allows natural or synthetic soundfields to be played back from a relatively small mechanical speaker structure, providing the benefits of multichannel sound without a cumbersome arrangement of individual speaker cabinets.

Abstract: A method for distribution multiple users of a soundfield having positional spatial components is disclosed including 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 the transmission signals to the multiple users; for each of the multiple users, determining a current orientation of a current user and producing a current orientation signal indicative thereof; utilising the current orientation signal to mix the transmission signals so as to produce sound emission source output signals for playback to the user. The soundfield signal can comprise a B-format signal which is suitably processed.

Abstract: The invention relates to an apparatus for sound reproduction of a sound information signal having spatial components, the apparatus includes:sound input means adapted to input the sound information signal;headtracking means for tracking a current head orientation of a listener listening to the sound information signal via sound emission sources and to produce a corresponding head orientation signal;sound information rotation means connected to the sound input means and the headtracking means and adapted to rotate said sound information signal to a substantially opposite degree to the degree of orientation of said current head orientation of the listener to produce a rotated sound information signal; andsound conversion means connected to the sound information rotation means for converting the rotated sound information signal to corresponding sound emission signals for outputting by the sound emission sources such that the spatial components of the sound information signal are substantially maintained in the p

Abstract: A method of processing audio input signals comprising 1-bit, Sigma-Delta Modulated (SDM) signals is disclosed including the steps of combining the audio input signals to form a combined audio input signal; and utilising a Sigma-Delta Modulator to convert the combined audio input signal to a corresponding Sigma-Delta Modulated output signal. The method can include a linear mix of the audio input signals and each audio input signal can multiplied by a corresponding gain factor before being added together with other of the audio input signals. The Sigma-Delta Modulator can include a noise shaping filter designed to amplify components of the audio input signals below a predetermined threshold frequency and the combining step can include utilising a negative feedback of the combined audio input signal. The noise shaping filter can utilise a series of integrating circuits as a means to decrease the sensitivity of the filter to errors in its coefficients.