The application describe a data processing system and associated methods for processing received speech data. The data processing system comprises: a classification unit configured to receive data derived from an audio signal and, based on the received data, to determine a classification state of an acoustic environment; wherein access to a subsequent processing unit is controlled based on the classification state of the acoustic environment. The classification state may be derived based on a pre-trained model, wherein the representation comprises a representation of the direct to reverberant ratio (DRR) of the audio signal.