Abstract: Reproduction of stereophonic audio information over a single speaker requires summing multiple stereo channels. When signals having approximately equal magnitudes and approximately opposite phases at a frequency are added together, the audio information at the frequency is lost. To preserve areas of potential cancellation and potential audio information loss, the audio enhancement system adjusts the phase relationship between the stereophonic channels. To avoid the loss of the spatial content of the stereo signal, the audio enhancement system determines the difference information that exists between different stereophonic channels. The audio enhancement system enhances the difference information and mixes the enhanced difference information with the phase adjusted signals to generate an enhanced monophonic output.

Abstract: A system and method for enhancement and management of streaming audio is disclosed. In one embodiment, the system provides a client-side decoder that is compatible with numerous audio formats, so that a user can enjoy relatively high-quality audio from various sources, even from sources that do not provide multi-channel or high-quality audio data. The system and method also include a management system for managing and controlling the use of licensed signal processing software to further enhance an audio stream. In one embodiment, the management system is used to manage a signal processing module that provides psychoacoustic audio processing to create a wider soundstage, an acoustic correction process to increase the perceived height and clarity of the audio image, and bass enhancement processing to create the perception of low bass from the small speakers or headphones typically used with multi-media systems and portable audio players.

Abstract: An audio enhancement system and method for use receives a group of multi-channel audio signals and provides a simulated surround sound environment through playback of only two output signals. The multi-channel audio signals comprise a pair of front signals intended for playback from a forward sound stage and a pair of rear signals intended for playback from a rear sound stage. The front and rear signals are modified in pairs by separating an ambient component of each pair of signals from a direct component and processing at least some of the components with a head-related transfer function. Processing of the individual audio signal components is determined by an intended playback position of the corresponding original audio signals. The individual audio signal components are then selectively combined with the original audio signals to form two enhanced output signals for generating a surround sound experience upon playback.

Abstract: A system and method for enhancement and management of streaming audio is disclosed. In one embodiment, the system provides a client-side decoder that is compatible with numerous audio formats, so that a user can enjoy relatively high-quality audio from various sources, even from sources that do not provide multi-channel or high-quality audio data. The system and method also include a management system for managing and controlling the use of licensed signal processing software to further enhance an audio stream. In one embodiment, the management system is used to manage a signal processing module that provides psychoacoustic audio processing to create a wider soundstage, an acoustic correction process to increase the perceived height and clarity of the audio image, and bass enhancement processing to create the perception of low bass from the small speakers or headphones typically used with multi-media systems and portable audio players.

Abstract: A system and method of remotely enabling sound enhancement techniques is disclosed. In an embodiment, a watermark is embedded in an encoded multi-channel audio stream to remotely enable an enhancement decoder portion of a multi-channel audio decoder.

Abstract: In certain embodiments, an improved audio equalization filter can be generated by frequency warping one or more digital filters having a plurality of frequency bands. Frequency warping can include, for example, transforming at least some of the frequency bands of the one or more digital filters into lower frequency bands. As a result, in various implementations the audio equalization filter may be more accurate than certain currently-available IIR equalization filters. The audio equalization filter may also be more computing-resource efficient than certain currently-available FIR equalization filters.

Abstract: A system and method for enhancement and management of streaming audio is disclosed. In one embodiment, the system provides a client-side decoder that is compatible with numerous audio formats, so that a user can enjoy relatively high-quality audio from various sources, even from sources that do not provide multi-channel or high-quality audio data. The system and method also include a management system for managing and controlling the use of licensed signal processing software to further enhance an audio stream. In one embodiment, the management system is used to manage a signal processing module that provides psychoacoustic audio processing to create a wider soundstage, an acoustic correction process to increase the perceived height and clarity of the audio image, and bass enhancement processing to create the perception of low bass from the small speakers or headphones typically used with multi-media systems and portable audio players.

Abstract: A stereo enhancement system processes the difference signal component generated from a pair of left and right input signals to create a broadened stereo image reproduced through a pair of speakers or through a surround sound system. Processing of the difference signal component occurs through equalization characterized by amplification of the low and high range of auditory frequencies. The processed difference signal is combined with a sum signal, generated from the left and right input signals, and the original left and right input signals to create enhanced left and right output signals.

Abstract: Systems and methods of processing audio signals are described. The audio signals comprise information about spatial position of a sound source relative to a listener. At least one audio filter generates two filtered signals for each of audio signal. The two filtered signals are mixed with other filtered signals from other audio signals to create a right output audio channel and a left audio output channel, such that the spatial position of the sound source is perceptible from the right and left audio output channels.

Abstract: A system and method for enhancement and management of streaming audio is disclosed. In one embodiment, the system provides a client-side decoder that is compatible with numerous audio formats, so that a user can enjoy relatively high-quality audio from various sources, even from sources that do not provide multi-channel or high-quality audio data. The system and method also include a management system for managing and controlling the use of licensed signal processing software to further enhance an audio stream. In one embodiment, the management system is used to manage a signal processing module that provides psychoacoustic audio processing to create a wider soundstage, an acoustic correction process to increase the perceived height and clarity of the audio image, and bass enhancement processing to create the perception of low bass from the small speakers or headphones typically used with multi-media systems and portable audio players.

Abstract: An acoustic correction apparatus processes a pair of left and right input signals to compensate for spatial distortion as a function of frequency when the input signals are reproduced through speakers in a sound system. The sound-energy of the left and right input signals is separated and corrected in a first low-frequency range and a second high-frequency range. The resultant signals are recombined to create image-corrected audio signals having a desired sound-pressure response when reproduced by the speakers in the sound system. The desired sound-pressure response creates an apparent sound image location with respect to a listener. The image-corrected signals may then be spatially enhanced to broaden the apparent sound image.

Abstract: An acoustic correction apparatus processes a pair of left and right input signals to compensate for spatial distortion as a function of frequency when said input signals are reproduced through loudspeakers in a sound system. The sound-energy of the left and right input signals is separated and corrected in a first low-frequency range and a second high-frequency range. The resultant signals are recombined to create image-corrected audio signals having a desired sound-pressure response when reproduced by the loudspeakers in the sound system. The desired sound-pressure response creates an apparent sound image location with respect to a listener. The image-corrected signals can also be spatially-enhanced to broaden the apparent sound image and improve the low frequency characteristics of the sound when played on small loudspeakers.

Abstract: Intelligibility of a human voice projected by a loudspeaker in an environment of high ambient noise is enhanced by processing a voice signal in accordance with the frequency response characteristics of the human hearing system. Intelligibility of the human voice is derived largely from the pattern of frequency distribution of voice sounds, such as formants, as perceived by the human hearing system. Intelligibility of speech in a voice signal is enhanced by filtering and expanding the voice signal with a transfer function that approximates an inverse of equal loudness contours for tones in a frontal sound field for humans of average hearing acuity.

Abstract: An acoustic correction apparatus processes a pair of left and right input signals to compensate for spatial distortion as a function of frequency when the input signals are reproduced through speakers in a sound system. The sound-energy of the left and right input signals is separated and corrected in a first low-frequency range and a second high-frequency range. The resultant signals are recombined to create image-corrected audio signals having a desired sound-pressure response when reproduced by the speakers in the sound system. The desired sound-pressure response creates an apparent sound image location with respect to a listener. The image-corrected signals may then be spatially-enhanced to broaden the apparent sound image.

Abstract: A stereo enhancement system processes the difference signal component generated from a pair of left and right input signals to create a broadened stereo image reproduced through a pair of speakers or through a surround sound system. Processing of the difference signal component occurs through equalization characterized by amplification of the low and high range of auditory frequencies. The processed difference signal is combined with a sum signal, generated from the left and right input signals, and the original left and right input signals to create enhanced left and right output signals.

Abstract: A sound enhancement system (synthesizer) disclosed. The enhancement system synthesizes pseudo-stereophonic left and right output channels output from a monophonic input channel. The monophonic input signal is applied to a perspective filter that produces a differential-mode signal and to an equalizer filter that produces a common-mode signal. The perspective filter attenuates signal components in a frequency range corresponding to the human voice. The equalizer filter attenuates signal components in a frequency range outside the frequency range of the human voice. The equalizer filter also provides a 90 degree phase shift. The differential-mode and the common-mode signals are combined to produce the output channels. The pseudo-stereo output provided by the synthesizer has relatively less ambience in the frequency range corresponding to the human voice and relatively more ambience in frequency ranges that do not correspond to the human voice.

Abstract: The present invention provides an audio enhancement apparatus and method which spectrally shapes harmonics of the low-frequency information in a pair of audio signals so that when reproduced by a loudspeaker, a listener perceives the loudspeaker as having more acoustic bandwidth than is actually provided by the loudspeaker. The perception of extra bandwidth is particularly pronounced at low frequencies, especially frequencies at which the loudspeaker system produces less acoustic output energy. In one embodiment, the invention also shifts signal from one audio signal to the other audio signal in order to obtain more bandwidth for the available loudspeaker to reduce clipping. In one embodiment, the invention also provides a combined signal path for spectral shaping of the desired harmonics and a feedforward signal path for each pair of audio signals.

Abstract: The present invention provides an audio enhancement apparatus and method which spectrally shapes the differential information in a pair of audio signals so as to create an immersive, three-dimensional effect when the audio signals are acoustically reproduced. In a preferred embodiment, the invention includes a two-transistor amplifier which spectrally shapes the differential information with what are called cross-over networks. The cross-over networks spectrally shape the differential information by selectively emphasizing or de-emphasizing certain frequencies in the differential information. In addition, the preferred embodiment adjusts the level of the sound which is common to both input signals to reduce clipping.

Abstract: An audio enhancement system and method for use in a surround sound environment creates a more diffuse and continuous sound field from a multi-channel, multi-speaker reproduction environment. Multiple audio source signals generated from an audio recording, which are intended for speakers placed in front of and behind a listener, are isolated into pairs and processed to create corresponding pairs of component audio signals. Each pair of component audio signals is generated, at least in part, from the information present in both corresponding audio source signals. The individual component audio signals are then selectively combined to form enhanced output signals so that each enhanced output signal is modified as function of a plurality of audio source signals.