Secure and/or comfortable retention of an earbud through a retainer contacting the concha of the ear

An earbud comprising:

• a housing of the earbud, and
• an arm extending at least partially from an aft portion of the earbud and configured to contact a concha of the ear when the earbud is seated in the ear,
• wherein the arm configured to permit at least a first portion of the arm to hinge away from the concha,
• wherein at least one of the first portion of the arm and a second portion of the arm follows a curvature of the concha,
• wherein the at least one of the first portion of the arm and the second portion of the arm follows the curvature of the concha at least to the interior surface of the anti-helix of the ear, and
• wherein the hinge element resists hinging away from the concha with a restoring force, such that when the earbud is seating in the ear the arm pushes off of at least one of the concha and an interior surface of an anti-helix of the ear to apply force toward at least one of (i) a front portion of the earbud and (ii) an ear tip of the earbud, to comfortably retain the earbud when the ear rests against a surface.