A method and an apparatus for transmitting a speech signal are provided. A
speech signal transmitter includes a quadrature mirror filter, a base
sub-band encoder, an enhancement sub-band encoder, and a network
connector. The quadrature mirror filter receives a speech signal, divides
the speech signal into an enhancement band speech signal and a base band
speech signal, and outputs the enhancement band speech signal and the
base band speech signal. The base sub-band encoder receives and encodes
the base band speech signal. The enhancement sub-band encoder receives
and encodes the enhancement band speech signal. The network connector
multiplexes the encoded enhancement band speech signal and the encoder
base band speech signal based on the kinds of networks over which speech
signals are transmitted, and transmits the multiplexed signals to the
networks. A speech signal s multiplexed and transmitted by various
methods based on the kinds of networks. Thus, the speech signal can be
efficiently transmitted.