Background noise contrast reduction for handovers involving a change of speech codec

摘要

During handover of a mobile communication unit from a first communication system having a first speech encoder 310 to a second communication system having a second speech encoder 330, a smooth transition of background noise is achieved by mixing 370 sampled noise from each encoder. As handover progresses noise from the first system is gradually decreased and faded out while noise from the second system is increased so that the user does not notice a change in noise level from one system to another. The sampled and mixed noise signal is inserted into any silent periods occurring near the handover point.