Leland Stanford Junior University

Media Vision

Other

Aureal Semiconductor, Inc.

Perry R Cook

Bryan J Colvin, Sr

Julius O Smith

Tom Lieber

Turner Evan Kirk

Jeffrey C Smith

Rebecca A Fiebrink

Daniel B Gochnauer

Leo Boyd

Mattias Ljungstroem

Ge Wang

Ari Lazier

Sinusoidal waveforms are synthesized using one or more waveguide resonance oscillators. The waveguide resonance oscillator has two digital delay elements coupled to a digital waveguide junction. Each digital delay element receives a signal on its respective input node and outputs the received signal on its respective output node after a delay of one sample period. In the preferred embodiment, the waveguide junction has three digital signal adders and one signal multiplier interconnected so as to compute, once each sample period, a new input value for each digital delay element as a function of the two signals output by the digital delay elements. The multiplier coefficient used by the waveguide junction's multiplier determines the generated waveform's frequency of oscillation. The two output signals from the waveguide junction are sinusoidal waveforms that are 90 degrees out of phase with each other. When the first multiplier's coefficient value is timing varying, the waveguide resonance oscillator generates a sinusoidal waveform of time varying frequency and a second multiplier is used in the waveguide junction to maintain the sinusoidal waveform at a substantially constant amplitude. By using a first waveguide resonance oscillator to control the multiplier coefficient of a second waveguide resonance oscillator, frequency modulated waveforms are generated by the second waveguide resonance oscillator.

System and method for real time sinusoidal signal generation using

Exponential and pseudo-exponential decay function values are generated by scaling a fractional decrease per sampling period by a previous decay function value and then subtracting the scaled fractional decrease from the previous decay function value. In one embodiment, a multiplier multiplies the fractional decrease by the previous decay function value and provides a product signal representing the scaled fractional decrease. An adder subtracts the scaled fractional decrease from the previous decay function value. In another embodiment, a shift block replaces the multiplier and approximates multiplication by a binary shift of the fractional decrease. The size of the shift is determined by the previous magnitude of the decay function as indicated by a priority encoder. Shifting generates a pseudo-exponential decay function which is suitable for music synthesis and can be generated quickly using less expensive hardware.

Economical generation of exponential and pseudo-exponential decay

Synthesizer models for emulating musical instruments can be improved using an analysis model that compares the output signal of the model to a recording of a desired sound and derives a residual signal that can be used to correct the model. When the original model is a good one, the residual signal is small and takes much less memory to store than is required for a sampled sound.

Residual excited wave guide

A speech synthesizer uses a digital waveguide network to simulate operation of the human pharynx on acoustic signals. One end of the digital waveguide network is connected to a glottal signal source, and another end has a signal filter simulating operation of the acoustic interface at a person's lips. The digital waveguide network has sets of waveguide sections connected in series by junctions, each waveguide section including two digital delay lines running parallel to each other for propagating signals in opposite directions. Each waveguide junction has associated reflection and propagation coefficients. A parameter library that stores sets of glottal source and waveguide junction control parameters for generating corresponding sets of predefined speech signals. The waveguide junction control parameters cause the digital waveguide network to simulate operation of an acoustic tube with a shape corresponding to that of a human pharynx while producing predefined speech sounds. An articulation controller operates the glottal signal source and the digital waveguide network using a sequence of selected sets of said control parameters, thereby causing the synthesizer to generate a specified sequence of speech signals. In a preferred embodiment, the digital waveguide network has three interconnected network branches for simulating operation of the lower pharynx, the oropharynx and the nasopharynx. To generate speech signals corresponding to fricative consonants, the speech synthesizer has noise signal injectors positioned at various points along the digital waveguide network.

Digital waveguide speech synthesis system and method

Synthesizer models for emulating musical instruments are improved to take into account sympathetic string vibrations. One embodiment of the present invention scales an output signal from a sound synthesis model and uses the scaled signal as an input signal for a number of single-string emulations causing the single-string emulations to produce sound signals corresponding to sympathetic string vibrations. The output signals from the synthesis model and from all of the single-string emulations are added together. Another embodiment employs an octave's worth of single-string emulations to emulate the lower strings of an emulated instrument. Still another embodiment is a synthesizer which includes an input bus for accepting a sound signal, scaling means, a plurality of single-string emulations, and means for summing output signals from the string emulations. Embodiments preferably employ waveguide synthesis or the plucked string model to emulate single-strings.

Sound synthesis model incorporating sympathetic vibrations of strings

A quasi-periodic signal is sampled at a specified rate, and then a predicted value of the signal is computed from a set of 2M+1 time lagged signal samples. The time lagged samples are centered in time at an integer multiple P of the signal's sampling period T.sub.s, where P.multidot.T.sub.s is approximately one period of the input signal. The predicted signal value is computed by multiplying each of the 2M+1 time lagged samples by a corresponding predictor coefficient c(i) and then summing the resulting products. The predicted signal value is subtracted from the actual signal value to obtain an error signal .epsilon.. During each successive sampling period, the predictor coefficients are updated by adjusting the previously computed predictor coefficients by an amount proportional to the error .epsilon. multiplied by each of the 2M+1 time lagged signal values. Using the updated coefficient values, a phase delay is computed, and then the signal's period is computed as the sum of phase delay and P.multidot.T.sub.s, which is the average integer time lag of the sampled signal values. When the phase delay is greater than one half of the sampling period T.sub.s, the value of P is increased or decreased, as necessary, to keep the time lagged signal samples approximately one period delayed from the current signal sample.

Accurate pitch measurement and tracking system and method

A programmable tone generator provides a signal that can be used by a hearing aid wearer to set the gain of the hearing aid such that the hearing threshold is at a prescribed corrected level.

Growing community of inventors

Palo Alto, CA, United States of America

Perry R Cook