EP0259950A1 Expired / Lapsed EP ⏱️ 0.0 years remaining

Digital speech sinusoidal vocoder with transmission of only a subset of harmonics

Assignee: AT&T Inc

•

Filing: 1987-07-06

•

Granted: —

•

Expires: 2007-07-06

📄 Original PDF 🌐 Google Patents 🔄 Sync Now

Abstract

Abstract A speech analyzer and synthesizer system using a sinusoidal encoding and decoding technique for voiced frames and noise excitation or multipulse excitation for unvoiced frames.For voiced frames, the analyzer (100) transmits the pitch, values for a subset of offsets defining differences between harmonic frequencies and a fundamental frequency, total frame energy, and linear predictive coding, LPC, coefficients. The synthesizer (200) is responsive to that information to determine the harmonic frequencies from the offset information for a subset of the harmonics and to determine the remaining harmonics from the fundamental frequency. The synthesizer then determines the phase for the fundamental frequency and harmonic frequencies and determines the amplitudes of the fundamental and harmonics using the total frame energy and the LPC coefficients. Once the phases and amplitudes have been determined for the fundamental and harmonic frequencies, the synthesizer performs a 'sinusoidal analysis. In another embodiment, the remaining harmonic frequencies are determined by calculating the theoretical harmonic frequencies for the remaining harmonic frequencies and grouping these theoretical frequencies into groups having the same number as the number of offsets transmitted. The offsets are then added to the corresponding theoretical harmonics of each of the groups of the remaining harmonic frequencies to generate the remaining harmonic frequencies. In a third embodiment, the offset signals are randomly permuted before being added to the groups of theoretical frequencies to generate the remaining harmonic frequencies.

Inventors

👤 Edward Charles Bronson
👤 Walter Thornley Hartwell
👤 Thomas Edward Jacobs
👤 Richard Harry Ketchum
👤 Willem Bastiaan Kleijn

Bibliographic Details

Application Number —

Jurisdiction EP

Data Source google_patents

Last Synchronized 2026-10-27 14:30

CPC Classifications

G; G10; G10L; G10L19/00; G10L19/04; G10L19/06; G10L19/07; G10L19/02; G10L19/08; G10L19/093

Claims Analysis

Total Claims: 8

Claim 1

Independent Claim 212 words

I. A processing system for encoding human speech comprising: a segmentor (102,141) for segmenting the speech into a plurality of speech frames, each having a predetermined number of evenly spaced samples of instantaneous amplitudes of speech and each of which overlaps by a predefined number of samples with the previous and subsequent frames; a LPC calculator (III) for calculating a set of speech parameter signals defining a vocal tract for each frame; a energy calculator (103) for calculating the frame energy per frame of the speech samples; CHARACTERIZED BY a spectral analyzer (142,143,144) for performing a spectral analysis of said speech samples of each frame to produce a spectrum for each frame; a pitch detector (109) for detecting the fundamental frequency signal for each frame from the spectrum corresponding to each frame; a harmonic peak locator (145) for determining a subset of harmonic frequency signals for each frame from the spectrum corresponding to each frame; a harmonic calculator (147) for determining offset signals representing the difference between each of said harmonic frequency signals and multiples of said fundamental frequency signal; and a parameter encoder (113) for transmitting encoded representations of said frame energy and said set of speech parameters and said fundamental frequency signal and said offset signals for subsequent speech synthesis.

Claim 2

Independent Claim 24 words

The system of claim I wherein said spectral analyzer comprises a sampler (142) for downsampling said speech samples thereby reducing the amount of computation.

Claim 3

Dependent Claim 124 words

The system of claim 2 wherein said pitch detector further designates frames as voiced and unvoiced, said system further comprises a noise/multipulse decision circuit (112) for transmitting a signal to indicate the use of noise-like excitation upon speech of said one of said frames resulting from noise-like source in the human larynx and said designating means indicating an unvoiced frame; a multipulse analyzer (110) for forming excitation information from a multipulse excitation source upon the absence of the noise-like source and upon said designating means indicating an unvoiced frame; and said parameter encoder further responsive to said multipulse excitation information and said set of speech parameters for transmitting encoded representations of multipulse excitation information and said set of speech parameters for subsequent speech synthesis.

Claim 4

Independent Claim 167 words

A method for synthesizing voice from encoded information representing speech frames each having a predetermined number of evenly spaced samples of instantaneous amplitude of speech with said encoded information for each frame comprising frame energy and a set of speech parameters and a fundamental frequency of speech and offset signals representing the difference between the theoretical harmonic frequencies as derived from a fundamental frequency signals and a subset of actual harmonic frequencies CHARACTERIZED BY calculating a subset of harmonic phase signals corresponding to said offset signals; computing the remaining harmonic phase signals for said one of said frames from said fundamental frequency signal; determining the amplitudes of said fundamental signal and said subset of harmonic phase signals and said remaining harmonic phase signals from the frame energy and the set of speech parameters of said one of said frame; and generating replicated speech in response to said fundamental signal and said subset and remaining harmonic phase signals and said determined amplitudes for said one of said frames.

Claim 5

Dependent Claim 49 words

The method of claim 4 wherein said computing step comprises the steps of multiplying each harmonic number with said fundamental frequency signal to generate a frequency for each of said remaining harmonic phase signals; arithmetically varying the generated frequencies; and calculating said remaining phase signals from said varied frequencies.

Claim 6

Dependent Claim 106 words

The method of claim 4 wherein said computing step comprises the steps of generating the remaining harmonic frequency signals corresponding to said remaining harmonic phase signals by multiplying said fundamental frequency signal by the harmonic number for each of said remaining harmonic signals; grouping the multiplied frequency signals into a plurality of subsets, each having the same number of harmonics as said subset of harmonic phase signal; adding each of said offset signals to the corresponding grouped frequency signals of each of said plurality of subsets to generate varied remaining harmonic frequency signals; and calculating said remaining harmonic phase signals from said varied harmonic frequency signals.

Claim 7

Dependent Claim 46 words

The method of claim 6 wherein said step of adding comprises the step of permuting the order of said offset signals before adding said signals to said corresponding grouped frequency signals of each of said plurality of subsets to generate said varied remaining harmonic frequency signals.

Claim 8

Dependent Claim 89 words

The method of claim 4 wherein said determining step comprises the steps of calculating the unscaled energy of each of said harmonic phase signals from said set of speech parameters for said one of said frames; summing said unscaled energy for all of said harmonic phase signals for said one of said frames; and computing the amplitudes of said harmonic phase signals in response to said harmonic energy of each of said harmonic signals and the summed unscaled energy and said frame energy for said one of said frames.

References Cited (Backward Citations)

WO1986005617A1 Cited

USPTO Annuity & Maintenance Windows

Maintenance schedule is calculated for granted US utility patents.

Assigned Categories & Tags

No categories assigned to this patent yet.

Assign Category Tag

Select Category

Notes (Optional)