The dialogue normalisation value is a Dolby Digital parameter that describes the long-term average dialogue level of the associated program. It may also describe the long-term average level of programmes that do not contain dialog, such as music. This level is specified on an absolute scale ranging from –1 dBFS to –31 dBFS. Dolby Digital decoders attenuate programmes based on the dialogue normalisation value in order to achieve uniform playback level.