发明名称 |
Enhanced conversion of wideband signals to narrowband signals |
摘要 |
Wideband speech signals must be converted to narrowband speech signals if the transmission medium or the destination terminal is constructed with narrowband constraints. A typical wideband-to-narrowband conversion method is the elimination of frequencies above 3400 Hz using a low pass filter and a down sampler. However, this method produces a muffled speech sound since the resulting narrowband signal has a flat frequency response. Methods and apparatus are presented herein to enhance the acoustic quality of a wideband-to-narrowband converted signal. A bandwidth switching filter is used to emphasize a mid-range frequency portion of the wideband signal so that the resulting narrowband signal has a non-flat frequency spectrum.
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申请公布号 |
US2003012221(A1) |
申请公布日期 |
2003.01.16 |
申请号 |
US20010771508 |
申请日期 |
2001.01.24 |
申请人 |
EL-MALEH KHALED H.;ANANTHAPADMANABHAN ARASANIPALAI K.;DEJACO ANDREW P. |
发明人 |
EL-MALEH KHALED H.;ANANTHAPADMANABHAN ARASANIPALAI K.;DEJACO ANDREW P. |
分类号 |
G10L21/04;G10L13/00;G10L19/14;G10L21/02;(IPC1-7):H04J3/16;H04J3/22 |
主分类号 |
G10L21/04 |
代理机构 |
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