Because all HTC races are conducted under RRCA liability insurance the use of headphones, baby joggers, etc are prohibited. While these devices may be OK for training runs (if used appropriately and safely) the crowded conditions of a race make them unsafe for the user as well as those around them. These regulations are for your safety and the safety of the runners around you. Please be considerate of others.
In addition, the USATF has banned headphones from all sanction events. You risk disqualification if caught wearing headphones. Headphones are any device worn in, on or around the ear for the purpose of listening to music or other audio not related to the ambient sounds of the environment.