Central Research Laboratories Limited

Thorn Emi Plc

Creative Technology Corporation

Alastair Sibbald

Richard David Clemow

Fawad Nackvi

Stanley Taylor

Elvin L Nix

Adam Rupert Philp

John Edward Shaw

Brian Holcroft

Peter D Whalley

Anthony Robert Corless

Elvin Leonard Nix

John Edward Andrew Shaw

Brian C Webb

Monica Backes

Ian Robins

Michael Jackson

Max Andrew Little

John F Ross

George Derek Warner

Gek K Chandler

Donald R Barron

Stephen D Evans

Stephen D Etienne

Terence Dean

Elaine Jackson

Adrian Miles Sandford

Michael Percy

Edward C Bell

A method of improving 3D sound reproduction is described, in which virtual sound sources to be positioned behind a listenerare filtered using an HF-cut filter in order to remove distracting high-frequency components caused by incomplete transaural crosstalk cancellation. Sound sources placed in the rearward hemisphere of reference sphereare filtered by an amount dependent on the position of the sound source in order to provide a smooth transition between the filtered and unfiltered hemispheres. HF-cut filtering is at a maximum when the sound source is placed directly behind the listener, and is progressively reduced as the forward hemisphere is approached. The invention offers an advantage in that virtual sound images may be placed more effectively behind the listener, given improved realism of 3D effects.

Method of improving 3D sound reproduction

A method and apparatus for improving the audibility of sound from a loudspeaker located close to an ear, comprises the steps of detecting ambient acoustic noise arriving from other sound sources using a transducer that provides corresponding ambient sound signals, inverting the polarity of said ambient sound signals and combining them with the signals being fed to the loudspeaker to reduce the audibility of said ambient acoustic noise, and passing said ambient sound signals through a filter having a predetermined average transfer function that compensates for the spectral modification of sounds travelling from the loudspeaker to the ear caused by the proximity of the ear of a listener in use.

Method of improving the audibility of sound from a loudspeaker located close to an ear

A method of processing a single channel audio signal to provide an audio source signal having left and right channels corresponding to a sound source at a given direction in space, includes performing a binaural synthesis introducing a time delay between the channels corresponding to the inter-aural time difference for a signal coming from said given direction, and controlling the left ear signal magnitude and the right ear signal magnitude to be at respective values. These values are determined by choosing a position for the sound source relative to the position of the head of a listener in use, calculating the distance from the chosen position of the sound source to respective ears of the listener, and determining the corresponding left ear signal magnitude and right ear signal magnitude using the inverse square law dependence of sound intensity with distance to provide cues for perception of the distance of said sound source in use.

Method of processing an audio signal

Original head-related transfer functions (HRTFs) are modified for a non-standard dimensioned head. The HRTF includes a near-ear response function, a far-ear response function, and an inter-aural time delay (ITD). The modified HRTF resembles an HRTF approximating that derived for a listener having different head and/or ear dimensions to the standard dimensions. The ITD value of the HRTF is multiplied by a given scaling factor independent of frequency. The near ear and/or far ear response function of the HRTF is multiplied by a constant scaling factor in the frequency domain independent of time delay, to expand or compress the functions in the frequency domain. The near ear and/or far ear response function of the HRTF are provided with a positive or negative offset value in the frequency domain. The amplitude of the near ear and/or far ear response function of the original HRTF(s) is (are) multiplied by a given gain factor.

Method of modifying one or more original head related transfer functions

A method of synthesizing an approximate impulse response function from a measured first impulse response function in a given sound field includes: sampling an early part of the impulse response for the given sound field; synthesizing a part impulse response which approximates to the sampled part of the given impulse response by curve fitting using a plurality of basis functions provided by respective multi-tap FIR filters, said part impulse response including scattering artefacts; synthesizing subsequent further part impulse responses using the same filters; applying an envelope function which decreases the amplitude with increasing time, and constructing an extended approximate impulse response by combining successive part impulse responses with irregular overlap to minimize audible artifacts. The synthesized impulse response function has psycho-acoustic properties similar to those of the original impulse response function, and enables fewer taps to be employed.

Method of synthesizing an approximate impulse response function

A method of audio signal processing for a loudspeaker located close to an ear in use, the method consisting of or including:- creating one or more derived signals from an original monophonic input signal, the derived signals being representative of the original signal being scattered by one or more bodies remote from said ear (excluding room boundary reflection or reverberation), combining the derived signal or signals with said input signal to form a combined signal, and feeding the combined signal to said loudspeaker, thereby providing cues for enabling the listener to perceive the source of the sound of the original monophonic input signal to be located remote from said ear.

Method of audio signal processing for a loudspeaker located close to an ear

A method of processing a plural channel audio signal representing a three dimensional sound-field for generation by respective left and right loudspeakers arranged at a given distance from a listener, including: a) choosing a distance between said loudspeakers and said listener; b) determining from this chosen distance an optimal amount of transaural acoustic crosstalk compensation, the optimal amount being a function of the chosen distance; and c) applying said optimal amount of crosstalk compensation to said left and right channels. The optimal transaural crosstalk cancellation is preferably achieved using a near ear response transfer function and a far ear response transfer function which asymptotically approach different values at low frequencies. The method may further include choosing an angle between the left channel loudspeaker and the right channel loudspeaker, and determining from both the chosen angle and the chosen distance an optimal amount of transaural crosstalk compensation.

Method of processing a plural channel audio signal

A stereo sound expander reproduces a realistic sound image in three dimensions by coupling modified and unmodified stereo signals. By not modifying a Head Related Transfer Function (HRTF) for one signal and equalizing the HRTF for the other signal, a flattened frequency response is produced with no tonal changes, but with a high degree of spatial accuracy. Resultant output signals may be used to generate binaural signals or can be fed into crosstalk cancellers.

Stereo sound expander

A method of synthesizing an audio signal having left and right channels corresponding to an extended virtual sound source at a given apparent location in space relative to a preferred position of a listener in use is described. The information in the channels includes cues for perception of the direction of said virtual sound source from the preferred position. The extended source comprises a plurality of point virtual sources, the sound from each point source being spatially related to the sound from the other point sources, such that sound appears to be emnitted from an extended region of space. If the signal from two sound sources is the same, they are modified to be sufficiently different from one another to be separately distinguishable by a listener when they are disposed symmetrically on either side of the listener. This modification can be accomplished by filtering the two point sources using different comb filters.

Method of synthesizing an audio signal

Apparatus for dispensing a predetermined volume of a liquid ( ) comprises a reservoir ( ) for the liquid, a channel ( ) provided with an outlet ( ) for conveying the liquid ( ) from the reservoir to the outlet, and means for generating a pulse of gas. The apparatus is arranged such that the flow of gas causes a predetermined volume of liquid to be ejected from the outlet. The outlet comprises a pair of openings in the channel which face one another, the liquid being retained between the openings by surface tension in the absence of a flow of gas. The gas flow is directed towards one of said openings in use. The apparatus may be used to dispense volumes of a liquid reagent in the range 1 nl to 2 &mgr;l. The apparatus avoids contamination of the liquid, and dispensing head construction allows devices to be low cost disposable units. The apparatus is less sensitive to liquid viscosity than existing devices.

Apparatus for dispensing a predetermined volume of a liquid

A laminated artificial pinna having a concha, fossa and auditory canal. The auditory canal is constructed and arranged relative to the concha so that the distance from the center of the entrance of the auditory canal to the rear wall of the concha lies within the range of 15 mm to 20 mm, the distance from the center of the entrance of the auditory canal to the concha floor lies within the range of 9 mm to 15 mm, and the alignment of the turning point with the center of the entrance of the auditory canal is substantially horizontal.

Artificial ear and auditory canal system and means of manufacturing the same

Stereophonic sound reproduction apparatus comprising an input means (2) for producing binaural signals, cross-talk cancellation means, (10) loudspeaker means, (20, 22) headphone means, (26) and a switch means (12, 18, 24, 30, 32) which in a first position (plug 24 not inserted in socket 18) couples the binaural signals from the input means (2) to the loudspeaker means (20, 22) through the cross-talk cancellation means (10) and in a second position (plug 24 inserted in socket 18) renders the cross-talk cancellation means (10) inoperable and couples the binaural signals from the input means (2) to the headphones (26).

Audio reproduction systems

Apparatus for audio signal stereophonic adjustment

Plural-channel sound processing

Apparatus for use with an autocorrelation technique for characterizing fingerprints includes an imaging device for providing an image of a fingerprint. The image so produced is then utilized by a microprocessor in order to generate an autocorrelation pattern for statistical comparison with stored data so as to determine whether the image of the fingerprint under test is derived from the fingerprint representated by the stored data.

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Maidenhead, United Kingdom

Alastair Sibbald