A pulling off sound generally means you are doing just that, pulling too much. Your hamstrings will work overtime and you will be utilizing more energy than needed.
Runners and triathletes need to focus on form just like all other athletes focus on form. If a football player tackles with poor form, his chances for injury go way up. If a swimmer does not focus on form, she is less efficient.
If you want to run pain-free and increase your performance, focusing on overall form is key. If the idea of listening to music is to tune your brain out, then it makes focusing on form extremely difficult.
Many endurance events do not allow the use of headphones. If you are training for 3.1, 13.1 or 26.2 miles—with or without a swim and bike before—mental toughness is the key to success.
How are you going to handle adversity? What will you do when the pain comes or you lose your salt tabs? Turn up the volume? Skip to your power song? Oops, Bieber and GaGa won't answer because they are not there. It's just you and the road.
Mental toughness comes long before the race, and music may not be there to motivate you. Is there a time and place for an iPod? Sure. If you are dialed into all of the above key elements, then enjoy your tunes every now and again. However, if you are like most endurance athletes, you are trying to improve your running performance and decrease your risk for injury. Improving takes focus and determination.
For some, ditching the headphones and music is like taking a binky away from a baby. Don't worry, your legs will still work and, who knows, you might even see some performance gains and enjoy your runs a little more.
Search for your next triathlon.