a) accessing at least part of a sound file as a plurality of bins, each bin storing a plurality of audio sections, wherein the plurality of audio sections is recorded nature sounds being rainfall sounds, and all of the sections in a first one of the bins have rainfall intensities that are lower than the rainfall intensities of all the sections in a second one of the bins;

b) executing an algorithm for forming a target sound sequence being a progression from light rainfall to heavy rainfall, wherein the algorithm selects selecting a plurality of selected audio sections from the plurality of bins and mixes the selected audio sections while cross fading to form the target sound sequence, the algorithm further makes gain adjustments on the target sound sequence as a function of simultaneously occurring reproduction of environment sound or an acoustic noise cancellation (ANC) process, and when making the gain adjustments as a function of the ANC process the target sound sequence is tailored and added to mask any remaining or residual audible effects of the ANC process; and

c) driving a speaker with the target sound sequence.