The Acting Secretary of the Army, the Honorable Patrick Murphy, signed an Army Directive May 6, 2016 updating a policy regarding Soldiers wearing headphones in uniform, specifically at fitness centers on military installations.
Army Directive 2016-20 references Army Regulation (AR) 670-1 and states that unless the unit or installation commander prohibits otherwise, Soldiers may use headphones in uniform while working out during individual physical training in indoor gyms and fitness centers. Soldiers may not wear headphones beyond the permitted area in any manner, including around the neck or attached to the uniform.
There are some uniformity regulations regarding the headphones. Ear pads cannot exceed 1.5 inches in diameter at the widest point, and Soldiers can wear a solid black armband for holding their authorized electronic devices in the gym or fitness center.
To view the updated AR 670-1 directive, visit http://www.apd.army.mil/pdffiles/ad2016_20.pdf.