Method for the modification of LPC coefficients of acoustic signals
US5732188A · kind A · utility
Assignee
Inventors
Key dates
| Filing date | Mar 11, 1996 |
| Grant date | Mar 24, 1998 |
| Priority date | — |
| Expiry date | Mar 11, 2016 |
Classification
- Technology area (CPC G)Physics
- CPC primaryG10L25/24
- WIPO fieldComputer technology
- WIPO sectorElectrical engineering
Abstract
In a CELP coding scheme, p-order LPC coefficients of an input signal are transformed into n-order LPC cepctrum coefficients c.sub.j (S.sub.2), which are modified into n-order modified LPC cepstrum coefficients c.sub.j ' (S.sub.3). Log power spectral envelopes of the input signal and a masking function suited thereto are calculated (FIGS. 3B, C), then they are subjected to inverse Fourier transform to obtain n-order LPC cepstrum coefficients, respectively, (FIGS. 3D, E), then the relationship between corresponding orders of the LPC cepstrum coefficients is calculated, and the modification in step S.sub.3 is carried out on the basis of the relationship. The modified coefficients c.sub.j are inversely transformed by the method of least squares into m-order LPC coefficients for use as filter coefficients of a perceptual weighting filter. This concept is applicable to a postfilter as well.
Source: USPTO / EPO open patent data. Objective bibliographic and citation counts.