A speech decoding device is provided is capable of reducing degradation of
speech quality caused by concealment processing performed when a loss of
a packet has occurred, e.g., in speech packet communications using a VoIP
(Voice over Internet Protocol) or the like. A decoding circuit decodes
speech from a packet received through an input terminal and stores an
internal signal in an updating buffer circuit, the internal signal
produced in the decoding process and to be used in a decoding process for
a subsequent packet to be subsequently received. The decoding circuit
produces, based on the internal signal stored in the updating buffer
circuit, concealed speech corresponding to a packet having not been
received, and outputs the produced concealed speech. The internal signal
is updated using the concealed speech.