1. An audio system, comprising: a filtered volume determiner configured to receive a first signal, wherein the filtered volume determiner is configured to generate a second signal corresponding to a volume envelope for a first range of selected frequencies of the first signal; a filtered noise generator configured to generate a third signal corresponding to noise substantially within a second range of selected frequencies; a signal modulator, coupled to the filtered volume determiner and to the filtered noise generator, wherein the signal modulator is configured to receive from the filtered volume determiner the second signal, and wherein the signal modulator is configured to receive from the filtered noise generator the third signal, and wherein the signal modulator is configured to generate a fourth signal substantially similar to a product of a weighted second signal and a weighted third signal; and a mixer, coupled to the signal modulator, wherein the mixer is configured to receive from the signal modulator the fourth signal, and wherein the mixer is configured to receive a fifth signal substantially similar to the first signal, and wherein the mixer is configured to generate a sixth signal substantially similar to a sum of a weighted fourth signal and a weighted fifth signal.