1. A method comprising: decoding compressed data using a dequantizer to recover high priority data from a received signal, the high priority data being associated with spectral envelope data of input data that was previously encoded as the received signal before the received signal was received; and recovering. from the received signal, low priority data associated with residual spectrum data of the input data using a side model, the side model being concurrently trained with the training of a quantizer used to encode the input signal, the quantizer trained with respect to the high priority data.