Fast telephone channel adaptation based on vector field smoothing technique

The paper presents a fast telephone channel adaptation method of MAP/VFS with a sequential training function. The concept is based on using maximum a posteriori (MAP) estimation as an intra-class training scheme in combination with vector field smoothing (VFS) technique as an inter-class training scheme. Experimental results of simultaneous adaptation to a telephone channel and a speaker show the proposed method is significantly superior to sequential MAP adaptation. The error reduction rate achieved in sequentially adapting a few words of sample data is about 41% using the proposed method, while that of the sequential MAP adaptation hardly improved even with ten-word adaptation data. MAP/VFS, with its fast and sequential adaptation function, is expected to be very useful in developing telephone applications such as information services proceeded by iterative tree-structured item selection