| 摘要 |
In order to suppress periodic noise, such as from a siren on a public safety vehicle or from a car engine, a speech signal having a periodic noise interferer is input to a speech processor in which the amplitude of the periodic noise is determined 72, a known gaussian noise sequence having the same amplitude as the periodic noise is generated 74 and combined 76 with the (speech + periodic noise signal) so that a standard wide-band noise suppression algorithm can be used in a noise suppressor 78 to suppress both the periodic noise and the gaussian noise. The noise suppressor 78 also provides an input to a sub-band gain adjustment block 80 so that an appropriate amount of the gaussian noise can be subtracted 82 from the output of the noise suppressor 78 to give an output speech signal with a greatly reduced periodic noise content. The arrangement may be used after a speech decoder (50, Fig.3) or in front of a speech encoder 84 in a mobile communications unit. |
