Method and apparatus for pre-processing speech signals prior to coding by transform-based speech coders
US6223151A · kind A · utility
Assignee
Inventors
Key dates
| Filing date | Feb 10, 1999 |
| Grant date | Apr 24, 2001 |
| Priority date | — |
| Expiry date | Feb 10, 2019 |
Classification
- Technology area (CPC G)Physics
- CPC primaryG10L19/09
- WIPO fieldComputer technology
- WIPO sectorElectrical engineering
Abstract
A method and apparatus which is used to precondition a speech signal such that the signal has relatively low power at predetermined points which form the boundaries of DFT blocks in a coder. The method and apparatus is particularly effective when the filter bank operates on a linear-prediction residual. The requirement of having low energy at the block boundary is well approximated by a requirement of having a pitch pulse near the center of the block. The method and apparatus makes it possible to make the difference between the original speech signal and the pre-processed speech signal inaudible or nearly inaudible. An AE coder which follows the pre-processor, therefore, reconstructs a quantized version of the pre-processed speech. The present invention differs from earlier pre-processors in its operation, in the properties of the modified speech signal, and in the fact that it is compatible with a sinusoidal or waveform-interpolation type of speech coder.
Source: USPTO / EPO open patent data. Objective bibliographic and citation counts.