In one embodiment, sound is delivered to the user through stereo headphones providing different content to each ear. In one embodiment, one ear hears the pitch sounds of Morse code, and the other ear hears the spoken language equivalent of the Morse signal. The timing of delivery of the pitch tones and spoken words is adaptable and may be shifted or computed for optimal cognitive benefit. For example, the presentation of a spoken word may be timed for delivery just at, just before, or just after the experimentally determined time for cognitive association by a standard user at a given Morse code reception skill level, thus either simulating or prompting recognition by the user at the cognitively optimal time. In a preferred embodiment, the left and right content comprise mixed audio, wherein a continuously variable ratio of tone-only and speech-only sources are presented by the device ranging from 100% tone/0% speech to 100% speech/0% tone in the opposing ears according to a cognitive effectiveness model. In one embodiment, the ear chosen for delivery of differential speech vs. tone input is selected based on cognitive models of differential left and right brain function as to cognitive factors such as music vs. speech. In one embodiment, aspects of the presentation of speech and tone are modulated according to the sensed physical activity, length of learning activity session, demonstrated progress towards competency, and total invested learning time of the user. For example, speech/tone ratio for each ear. Morse code speed, intercharacter or interword spacing, time shift between speech and tone presentation, and/or time shift between speech or tone presentation and user's vocal or other responses may be modulated. In a preferred embodiment, the user must acknowledge a licensing agreement or requirement for external action in order to activate or use the system. For example, the device may require the user to acknowledge the importance or necessity of obtaining approval of a doctor before engaging in strenuous exercise. Similarly the user may be required to agree to use the device, methods and systems only in a safe manner, such as to ensure the user has determined in their sole judgment that there is no risk of accident or injury in using the device.