The present invention relates to a method and device for improving
concealment of frame erasure caused by frames of an encoded sound signal
erased during transmission from an encoder (106) to a decoder (110), and
for accelerating recovery of the decoder after non erased frames of the
encoded sound signal have been received. For that purpose,
concealment/recovery parameters are determined in the encoder or decoder.
When determined in the encoder (106), the concealment/recovery parameters
are transmitted to the decoder (110). In the decoder, erasure frame
concealment and decoder recovery is conducted in response to the
concealment/recovery parameters. The concealment/recovery parameters may
be selected from the group consisting of: a signal classification
parameter, an energy information parameter and a phase information
parameter. The determination of the concealment/recovery parameters
comprises classifying the successive frames of the encoded sound signal
as unvoiced, unvoiced transition, voiced transition, voiced, or onset,
and this classification is determined on the basis of at least a part of
the following parameters: a normalized correlation parameter, a spectral
tilt parameter, a signal-to-noise ratio parameter, a pitch stability
parameter, a relative frame energy parameter, and a zero crossing
parameter.