A system, methods, and devices that allow a listener to compensate for variability in the physical configuration and characteristics of individual ears to optimize the sound quality and listening experience for sound reproduction or amplification through an earphone, earbud, hearing aid, or the like. The present invention comprises one or more earphones, earbuds, hearing aid, dongle, or similar devices with an equalizer or equalizing circuitry or processing program contained therein, or in a circuit with the earphone, earbud, hearing aid or similar device. The equalizer or equalizing circuitry or processing program may be located in a separate device attached or in electronic communication, wired or wirelessly, to the earphone, earbuds or hearing aid, such as a remote. It also may be located in the sound-providing or music-providing device. The equalizer settings can be adjusted manually or automatically for each ear. An amplifier, or amplifying circuitry, also may be present.