Harman International Industries, Inc.

Lexicon, Inc.

David H Griesinger

A downmixer provides a listener of an output signal with a substantially accurate rendition of the apparent direction and relative loudness of an input signal. Downmixing certain channels of the input signal independently may substantially preserve the energy and intended direction of the input signal. The downmixer may include a test downmixer that operates over a limited frequency range to more accurately reflect the loudness of the input signal at the output, as perceived by a listener. The downmixer may demand fewer resources, freeing up resources for use in other operations.

Multichannel downmixing device

The beginning detection, accommodation and frequency bias properties of the human hearing mechanism have been modeled to create systems that can detect directional transients ('sound events') in a sound field and localize them. These systems break down a sound field into sound events and non-sound events and separately localize the sound events and non-sound events. Sound events are generally identified according to the frequency bias and beginning detection properties. Once detected, the sound events are generally localized according to differential steering angles (steering angles to which the steady-state signals have been accommodated) or ordinary steering angles, both of which reflect the direction of a sound event indicated during the rise-time of the sound event. When no sound events are detected, non-sound events are localized according to a steering angle that does not reflect rapid motion.

Sound event detection and localization system using power analysis

Sound event detector system

Sound localization system based on analysis of the sound field

A method and system are provided for generating one or more mix coefficients for downmixing a multichannel input signal having a plurality of input channels, to an output signal having a plurality of output channels. Mix coefficients may be generated responsive to a comparison of energy between the downmixed (output) signal and the input signal to the downmixer, such that energy and intended direction of the input signal are substantially preserved in the output signal. Further, or in the alternative, the mix coefficient generation may preserve an intended direction of an input signal, for example, received at a surround input channel, in at least one output channel of the output signal. The mix coefficient values may be generated in a test downmixer environment. Additionally, one or more mix coefficients may be generated by retrieving predetermined mix coefficient values. Additionally, or in the alternative, one or more mix coefficients may be generated responsive to an input energy of a plurality of the input channels.

A sound processing system increases the robustness of surround sound in various playback situations. The system may process an incoming signal, such as a five channel surround sound signal, with a first and a second matrix. The first and second matrices produce outputs signals from the input incoming signals. At least one of the output signals may be combined before being sent to the speakers.

Discrete surround audio system for home and automotive listening

A sound reproduction system has been developed, for converting signals on two input channels into surround signals on five or seven output channels and vice-versa. A decoder is included in the sound reproduction system which enhances the correlated component of the input signals in the desired direction and reduces the strength of such signals in channels not associated with the encoded direction, while preserving the apparent loudness of all output channels, the separation between the respective left and right output channels and the total energy of the uncorrelated component of the input channels in each output channel. The decoder may include a uniquely defined matrix that helps to ensure that the surface of the output signals is smooth and continuous.

5-2-5 matrix encoder and decoder system

A sound reproduction system has been developed, for converting signals on two input channels into surround signals on five or seven output channels and vice-versa. A decoder is included which enhances the correlated component of the input signals in the desired direction and reduces the strength of such signals in channels not associated with the encoded direction, while preserving the apparent loudness of all output channels, the separation between the respective left and right output channels and the total energy of the uncorrelated component of the input channels in each output channel. Included within the decoder is a uniquely defined matrix that helps to ensure that the surface of the output signals is smooth and continuous. An encoder is also included which encodes five or seven channels of sound into two so the two channels may be decoded by a variety of decoders with the correct sound direction and level.

A method and system for providing enhanced coupling of a stereophonic pair of full-range loudspeakers or subwoofers to all room modes of a laterally symmetric listening room wherein the preferred location of a listener is on the lateral center line thereof, by applying the left and right audio signals or the low frequency components thereof through a pair of all-pass phase shift networks having an in-phase relationship at higher audio frequencies and an approximately quadrature phase relationship at low audio frequencies where localization is not possible. The method and system may further be compensated by a 3 dB bass boost in each channel to provide the same sound pressure level at low frequencies as would occur with a pair of subwoofers placed together in one comer of the room and driven in phase, thereby ensuring a constant sound pressure level along the lateral center line of the listening room at all audio frequencies.

Method and system for driving speakers with a 90 degree phase shift

A sound reproduction system for converting stereo signals on two input channels, which may have been directionally encoded from a four or five channel original using a phase/amplitude film matrix encoder, such signals including at least one component which is directionally encoded through a phase and amplitude encoding device and at least one component that is not directionally encoded but is different in the two input channels, into signals for multiple output channels, for example center, front left, front right, side left, side right, rear left, and rear right, including decoding apparatus for enhancing the directionally encoded component of the input signals in the desired direction and reducing the strength of such signals in channels not associated with the encoded direction, while preserving both the maximum separation between the respective left and right channels and the total energy of the non-directionally encoded component of the input channels in each output channel, such that the instruments recorded on the right input channel stay on the right side of the output channels and the instruments recorded on the left stay on the left side, and the apparent loudness of all the instruments in all the output channels stays the same regardless of the direction of the directionally encoded component of the input signals; and further including circuits to improve separation in the decoder for uncorrelated left and right side inputs, to improve reproduction of apparent motion between the sides and the rear, to compensate for boost applied to signals in the front quarter of the sound field, and to limit the maximum excursion of each of the direction control signals when the other is changing.

Multichannel active matrix encoder and decoder with maximum lateral

A sound reproduction system for converting stereo signals on two input channels, which may have been directionally encoded from a four or five channel original using a phase/amplitude film matrix encoder, such signals including at least one component which is directionally encoded through a phase and amplitude encoding device and at least one component that is not directionally encoded but is different in the two input channels, into signals for multiple output channels, for example center, front left, front right, side left, side right, rear left, and rear right, including decoding apparatus for enhancing the directionally encoded component of the input signals in the desired direction and reducing the strength of such signals in channels not associated with the encoded direction, while preserving both the maximum separation between the respective left and right channels and the total energy of the non-directionally encoded component of the input channels in each output channel, such that the instruments recorded on the right input channel stay on the right side of the output channels and the instruments recorded on the left stay on the left side, and the apparent loudness of all the instruments in all the output channels stays the same regardless of the direction of the directionally encoded component of the input signals.

Multichannel active matrix sound reproduction with maximum lateral

A process for evaluating spatial impression of an enclosed space includes the steps of generating output signals as a function of fluctuating sound pressure at two points spaced about one-quarter meter apart, band limiting the output signals to a pass band of less than about one octave, generating fluctuating signals that represent amplitude information of the band limited output signals, band limiting the fluctuating amplitude information signals to a pass band of about five hertz to thirty hertz, and comparing the band limited fluctuating amplitude information signals to provide an indication of the spatial impression of the enclosed space.

Acoustic analysis

A sound reproduction system for converting encoded stereo signals on input channels A and B into signals on left, supplemental left, right, and supplemental right output channels, respectively, that includes a left output channel for producing output signals intended to come from the left direction; a supplemental left output channel for producing output signals similar in level (intensity) to output signals of the left output channel and with reduced steered signal level for left direction signals; a right output channel for producing output signals intended to come from the right direction; and a supplemental right output channel for producing output signals similar in level (intensity) to output signals on the right output channel and with reduced steered signal level for right direction signals.

Sound reproduction

An electroacoustic system for acoustic enhancement of a room that includes a sound source location. The electroacoustic system includes a microphone spaced from the sound source location, an array of loudspeakers arranged in at least four interleaved banks, each bank including at least one loudspeaker, and signal processing electronics connected between the microphone and the speaker banks that includes an input channel, circuitry connecting the microphone to the input channel, a plurality of output channels corresponding in number to the number of speaker banks, circuitry connecting each output channel to a corresponding speaker bank, and at least four statistically independent time-variant reverberation units responsive to input signals from the microphone for producing output signals on the output channels for driving the several banks of speakers.

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Cambridge, MA, United States of America

David H Griesinger