A method performed by one ore more computing devices, the method comprising: receiving an audio signal that comprises audio content and one or more sets of differential gains; identifying a specific set of differential gains, among the one or more sets of differential gains, for a gain profile in a specific playback environment; generating a set of default gains based at least in part on a default dynamic range compression curve related to the specific set of differential gains; and based at least in part on a combination of the set of default gains and the specific set of differential gains, performing one or more operations on one or more portions of the audio content extracted from the audio signal; characterized in that said performing one or more operations on one or more portions of the audio content extracted from the audio signal uses a loudness level determined from each of the one or more portions of the audio content; and in that the method further comprises: maintaining a histogram of instantaneous loudness levels, the histogram being populated by instantaneous loudness levels computed from a time interval in the audio content previous to the one or more portions of the audio content; determining whether a specific loudness level is below a threshold in a high probability area of the histogram, the specific loudness level being computed from a portion of the audio content among the one or more portions; and in response to determining that the specific loudness level is below the threshold in the high probability area of the histogram, performing: determining that a loudness transition occurs for the portion of the audio content from which the specific loudness level is computed; and shortening a time constant used in smoothing to speed up the loudness transition. receiving an audio signal that comprises audio content and one or more sets of differential gains; identifying a specific set of differential gains, among the one or more sets of differential gains, for a gain profile in a specific playback environment; generating a set of default gains based at least in part on a default dynamic range compression curve related to the specific set of differential gains; and based at least in part on a combination of the set of default gains and the specific set of differential gains, performing one or more operations on one or more portions of the audio content extracted from the audio signal; characterized in that said performing one or more operations on one or more portions of the audio content extracted from the audio signal uses a loudness level determined from each of the one or more portions of the audio content; and in that the method further comprises: maintaining a histogram of instantaneous loudness levels, the histogram being populated by instantaneous loudness levels computed from a time interval in the audio content previous to the one or more portions of the audio content; determining whether a specific loudness level is below a threshold in a high probability area of the histogram, the specific loudness level being computed from a portion of the audio content among the one or more portions; and in response to determining that the specific loudness level is below the threshold in the high probability area of the histogram, performing: determining that a loudness transition occurs for the portion of the audio content from which the specific loudness level is computed; and shortening a time constant used in smoothing to speed up the loudness transition. maintaining a histogram of instantaneous loudness levels, the histogram being populated by instantaneous loudness levels computed from a time interval in the audio content previous to the one or more portions of the audio content; determining whether a specific loudness level is below a threshold in a high probability area of the histogram, the specific loudness level being computed from a portion of the audio content among the one or more portions; and in response to determining that the specific loudness level is below the threshold in the high probability area of the histogram, performing: determining that a loudness transition occurs for the portion of the audio content from which the specific loudness level is computed; and shortening a time constant used in smoothing to speed up the loudness transition. determining that a loudness transition occurs for the portion of the audio content from which the specific loudness level is computed; and shortening a time constant used in smoothing to speed up the loudness transition.