Abstract: A method of reducing noise in an audio signal, comprising the steps of: using a furrow filter to select spectral components that are narrow in frequency but relatively broad in time; using a bar filter to select spectral components that are broad in frequency but relatively narrow in time; analyzing the relative energy distribution between the output of the furrow and bar filters to determine the optimal proportion of spectral components for the output signal; and reconstructing the audio signal to generate the output signal. A second pair of time-frequency filters may be used to further improve intelligibility of the output signal. The temporal relationship between the furrow filter output and the bar filter output may be monitored so that the fricative components are allowed primarily at boundaries between intervals with no voiced signal present and intervals with voice components. A noise reduction system for an audio signal.

Abstract: The present invention provides apparatus and methods which allow music synthesis and audio processing tasks to dynamically scale from a default processor to additional processors in a heterogeneous array of processors in a manner transparent to the user. A router running on one of the processors in the array knows or estimates the load on each processor, and dynamically allocates processing tasks based upon the current load on each processor and its capacity. Processing parameters are shared between all the audio processors to ensure that perceived audio quality is independent of where a task is running.

Abstract: A spatial enhancement system broadens the sound image of a stereo signal. The system emphasizes dissimilarity between the left and right channels by (i) boosting the level of the dissimilar components, (ii) providing spectral equalization to enhance the perception of breadth, and (iii) injecting an equalized, attenuated and inverted version of the dissimilar component into the opposite channel to broaden the components stereo image. The present invention avoids spectral coloration by providing a generally flat transfer function from input to output. Interchannel dissimilarity is estimated by performing a first order comparison of the left and right input signals. The comparison may be implemented by a peak detector on the L-R signal, a cross-correlation procedure, or some other scheme. As a feature, a feedback mechanism alters the equalization characteristics of the signals in a manner that is responsive to the dissimilarity of the output signals.

Abstract: Audio spatial localization is accomplished by utilizing input parameters representing the physical and geometrical aspects of a sound source to modify a monophonic representation of the sound or voice and generate a stereo signal which simulates the acoustical effect of the localized sound. The input parameters include location and velocity, and may also include directivity, reverberation, and other aspects. The input parameters are used to generate control parameters which control voice processing. Thus, each voice is Doppler shifted, separated into left and right channels, equalized, and one channel is delayed, according to the control parameters. In addition, the left and right channels may be separated into front and back channels, which are separately processed to simulate front and back location and motion. The stereo signals may be fed into headphones, or may be fed into a crosstalk cancellation device for use with loudspeakers.