Voiced/unvoiced information estimation system and method therefor

• US 20020062209A1
• Filed: 07/03/2001
• Published: 05/23/2002
• Est. Priority Date: 11/22/2000
• Status: Active Grant

• Current Assignee: Ericsson-LG Enterprise Co., Ltd (Telefonaktiebolaget LM Ericsson)
• Original Assignee: LG Electronics, Inc. (LG Corporation)
• Inventors: Choi, Yong Soo
• Granted Patent: US 7,016,832 B2
• Time in Patent Office: Days
• US Class Current: 704/208
• CPC Class Codes: G10L 2025/937 Signal energy in various frequency bands
• CPC Class Codes: G10L 25/93 Discriminating between voiced and unvoiced parts of speech signals G10L25/90 takes precedence

Abstract

A voiced/unvoiced information estimation system uses input spectrum and synthetic spectrum to produce a voicing level spectrum. The estimation system uses a spectrum difference calculation unit to normalize a spectrum difference energy for each harmonic band in unit of harmonic band, and further uses a voicing level calculation unit to calculate a voicing level. The voicing level of each harmonic band has a continuous value between 1 and 0. The estimation system is effective in vector quantization of voiced/unvoiced information at a low bit rate. Because it is unnecessary to calculate a threshold for deciding a voiced/unvoiced information, a decision anomaly occurring due to threshold is eliminated, and the accuracy of a voicing level is improved. Furthermore, since a spectrum is represented by mixing a voiced element and a unvoiced element in a harmonic band, the estimation system improves the audio quality of a combined sound.

Claims

1. A method of estimating voiced/unvoiced information from a voice input signal, the method comprising the steps of:

transforming the voice input signal into an input spectrum having input spectrum energy;

obtaining a synthetic spectrum having synthetic spectrum energy using at least one of a fundamental frequency, a harmonic size and a window spectrum;

determining at least one voice level decision band from the input spectrum and the synthetic spectrum;

determining a band spectral difference energy for the voice level decision band by finding difference between the input spectrum energy and the synthetic spectrum energy;

normalizing the band spectral difference energy with the input spectrum energy to determine a normalized spectra difference energy; and

calculating a voicing level corresponding to the voice level decision band using the normalized spectra difference energy.

2. The method of claim 1, wherein the voicing level is calculated by subtracting the normalized spectra difference energy from 1.

3. The method of claim 2, wherein the voicing level is set to a value between 0 and 1.

4. The method of claim 1, further comprising the step of determining a plurality of voice level decision bands from the input spectrum and the synthetic spectrum, wherein the voicing level is determined for each one of the plurality of voice level decision bands.

5. The method of claim 4, wherein there are L voice level decision bands, L having a value between 10 and 60.

6. The method of claim 1, wherein the voice input signal is transformed into the input spectrum having input spectrum energy using Fourier transformation.

10. The method of claim 1, wherein L has a value between 10 and 60.

7. A method of estimating voiced/unvoiced information from a voice input signal, the method comprising the steps of:

transforming the voice input signal into an input spectrum having input spectrum energy;

obtaining a synthetic spectrum having synthetic spectrum energy using at least one of a fundamental frequency, a harmonic size and a window spectrum;

determining L voice level decision band from the input spectrum and the synthetic spectrum, wherein L is an integer;

determining a corresponding band spectral difference energy for each voice level decision band by finding difference between the respective input spectrum energy and the respective synthetic spectrum energy;

normalizing the band spectral difference energy with the input spectrum energy to determine a normalized spectra difference energy for respective voice level decision band; and

calculating a voicing level corresponding to the respective voice level decision band using the normalized spectra difference energy.

8. The method of claim 7, wherein the voicing level is calculated by subtracting the normalized spectra difference energy from 1.

9. The method of claim 8, wherein the voicing level is set to a value between 0 and 1.

11. An estimation system for estimating voiced/unvoiced information from a voice input signal, the estimation system comprising:

means for transforming the voice input signal into an input spectrum having input spectrum energy;

means for obtaining a synthetic spectrum having synthetic spectrum energy using at least one of a fundamental frequency, a harmonic size and a window spectrum;

means for determining at least one voice level decision band from the input spectrum and the synthetic spectrum;

means for determining a band spectral difference energy for the voice level decision band by finding difference between the input spectrum energy and the synthetic spectrum energy;

means for normalizing the band spectral difference energy with the input spectrum energy to determine a normalized spectra difference energy; and

means for calculating a voicing level corresponding to the voice level decision band using the normalized spectra difference energy.

12. The estimation system of claim 11, wherein the means for calculating the voicing level subtracts the normalized spectra difference energy from 1 to find the voicing level.

13. The estimation system of claim 12, wherein the voicing level is set to a value between 0 and 1.

14. The estimation system of claim 11, further comprising a plurality of voice level decision bands is determined from the input spectrum and the synthetic spectrum, wherein the voicing level is determined for each one of the plurality of voice level decision bands.

15. The estimation system of claim 14, wherein there are L voice level decision bands, L having a value between 10 and 60.

16. The estimation system of claim 11, wherein the voice input signal is transformed into the input spectrum having input spectrum energy using Fourier transformation.

18. The estimation system of claim 17, wherein the voicing level calculation unit subtracts the normalized spectra difference energy from 1 to find the voicing level.

19. The estimation system of claim 18, wherein the voicing level is set to a value between 0 and 1.

20. The estimation system of claim 17, wherein a plurality of voice level decision bands is determined from the input spectrum and the synthetic spectrum, wherein the voicing level is determined for each one of the plurality of voice level decision bands.

17. An estimation system for estimating voiced/unvoiced information from a voice input signal, the estimation system comprising:

means for transforming the voice input signal into an input spectrum having input spectrum energy;

means for obtaining a synthetic spectrum having synthetic spectrum energy using at least one of a fundamental frequency, a harmonic size and a window spectrum;

a spectrum difference calculation unit to determine at least one voice level decision band from the input spectrum and the synthetic spectrum and to determine a band spectral difference energy for the voice level decision band by finding difference between the input spectrum energy and the synthetic spectrum energy and normalizing the band spectral difference energy with the input spectrum energy to determine a normalized spectra difference energy; and

a voicing level calculation unit to calculating a voicing level corresponding to the voice level decision band using the normalized spectra difference energy.