Frame recovery after frame loss using LSF stabilization

There is provided an Audio decoder (100) for synthesizing an audio signal from a bitstream which represents the audio signal, the audio decoder (100) including:a bitstream receiver (5), to receive the bitstream representative of the audio signal, the bitstream having, encoded therein, a set of encoded audio parameters (ΔLSF_q) for each frame of the audio signal,a first audio parameter decoding unit (10), to decode, for a current properly received frame, a first set of decoded audio parameters (a_i1) from at least the set of encoded audio parameters,a concealment unit (40) to conceal at least one non-properly received frame based on at least one previously properly received frame, so as to generate at least one set of concealment audio parameters;a second audio parameter decoding unit (20), to decode, for a current properly received frame which immediately follows the at least one previously non-properly received frame, a second set of decoded audio parameters (a_i2) from at least the set of encoded audio parameters, the second set of decoded audio parameters (a_i2) being different from the first set of decoded audio parameters (a_i1);a synthesizing unit (50), to output, or derive, an output or derived version of the synthesized audio signal in such way that, if the current properly received frame immediately follows the at least one previously non-properly received frame, a selection (60) is made between:a first version (s1) of the synthesized audio signal, synthesized from at least the first set of decoded audio parameters; anda second version (s2) of the synthesized audio signal, synthesized from the second set of decoded audio parameters.