Digital audio supplementation

A digital sound file stored on a tangible, non-transitory medium and made by a process of steps that comprise:

• identifying a tangibly-stored digital sound file that contains data for producing audible sound content in the form of speaking, music, or both;
• identifying and selecting, with a digital sound processing system that modifies audio files, a digital source of supplemental non-harmonic sound content to be added to the audible sound content of the digital sound file;
• accessing a copy of the digital sound file, with the digital sound processing system, to edit data in the digital sound file that contains the data for producing the audible sound content;
• electronically adding the supplemental non-harmonic sound content to the audible sound content across a substantial length of the audible sound content, with the digital processing system, to produce supplemented sound content, wherein the supplemental non-harmonic sound content has a sub-audible volume with a frequency range that would be audible if it was provided at an audible volume;
• and
• digitally storing the supplemented sound content as a digital combination of the audible sound content and the supplemental sub-audible non-harmonic sound content in a format that the digital combination can subsequently be played together as one presentation to one or more users as concurrent audible and sub-audible sound.

A device containing one or more tangible, non-transitory machine-readable storage media that store instructions that, when executed by one or more computer processors, perform operations comprising:

• identifying a tangibly-stored digital sound file that contains data for producing audible sound content in the form of speaking, music, or both;
• identifying and selecting, with a digital sound processing system that modifies audio files, a digital source of supplemental non-harmonic sound content content to be added to the audible sound content of the digital sound file;
• accessing a copy of the digital sound file, with the digital sound processing system, to edit data in the digital sound file that contains the data for producing the audible sound content;
• electronically adding the supplemental non-harmonic sound content to the audible sound content across a substantial length of the audible sound content, with the digital processing system, to produce supplemented sound content, wherein the supplemental non-harmonic sound content has a sub-audible volume in the supplemented sound content with a frequency range that would be audible if it was provided at an audible volume;
• and
• digitally storing the supplemented sound content as a digital combination of the audible sound content and the supplemental sub-audible non-harmonic sound content in a format that the digital combination can subsequently be played together as one presentation to one or more users as concurrent audible and sub-audible sound.