FIM Rules:
Nothing in the rules specifically prohibits it, but the safety officials have plenty of discretion to bar unsafe conditions like that.
There is a moto-journo I know who would be listening to his iPod at every press intro I went to. At the Buell 2007 product intro (
http://www.motorcycle.com/manufactu...-and-an-xbrr-buells-in-bakersfield-14289.html) I saw him putting his earphones in--getting ready to ride on the track at Buttonwillow! "Hey," I said, "don't ever let anybody see you wear those things at a press intro, especially not at a trackday!" He blew me off.
Not long after, disaster struck when he crashed at Laguna during the R1 press intro. Was he wearing his headphones? I think yes.
Anyway, here are the FIM rules regulating equipment:
2.12 Protective Clothing and Helmets
2.12.1 Riders must wear a complete leather suit with additional leather
padding or other protection on the principal contact points, knees,
elbows, shoulders, hips etc.
2.12.2 Linings or undergarments must not be made of a synthetic material
which might melt and cause damage to the riders' skin.
2.12.3 Riders must also wear leather gloves and boots, which with the suit
provides complete coverage from the neck down.
2.12.4 Leather substitute materials may be used, providing they have been
checked by the Chief Technical Scrutineer.
2.12.5 Use of a back protector is highly recommended.
2.12.6 Riders must wear a helmet which is in good condition, provides a
good fit and is properly fastened.
2.12.7 Helmets must be of the full face type and conform to one of the
recognised international standards:
• Europe ECE 22-05 ‘P’
• Japan JIS T 8133 : 2000
• USA SNELL M 2005
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2.12.8 Visors must be made of a shatterproof material.
2.12.9 Disposable "tear-offs" are permitted.
2.12.10 Any question concerning the suitability or condition of the riders
clothing and/or helmet shall be decided by the Technical Director, who
may, if he so wishes, consult with the manufacturers of the product
before making a final decision.