Over the Ear Headphones

• Over the ear headphones fit over the user's ears.Hemera Technologies/PhotoObjects.net/Getty Images
  
  Preferred by many studio producers, over the ear headphones feature padded cups that fit over the user's ear, sealing the sound-generating element of the headphone and trapping most noise. Additionally, the speaker components of all over the ear headphones project sound directly into the ear canal, unlike other models that project sound at an angle. However, some over the ear headphones, particularly those favored by studio musicians and producers, are so powerful they project deep bass or high tenor notes away from the user, causing some sound bleed.
  
  

Intra-concha Ear Buds

• Intra-concha ear buds fit into the outer ear.Jupiterimages/Photos.com/Getty Images
  
  Intra-concha ear buds, commonly referred to as "ear buds" fit inside the outer ear, resting just above the ear's inner canal. As with over the ear headphones, they project noise directly into the ear canal. Because of their closer proximity, however, ear buds can be used effectively at a lower volume. Because they lack the padding and insulation of over the ear headphones, ear buds can emanate a lot of ambient noise away from the user if they are played at high volumes. In most cases, however, volumes that could emanate ambient noise would result in an uncomfortable or even potentially harmful listening experience for the user.
  
  

Intra-canal Ear Buds

• Intra-canal ear buds fit directly into the ear canal.Ethan Miller/Getty Images News/Getty Images
  
  Representing an advancement in ear bud technology, intra-canal ear buds fit inside the inner ear canal, typically using a rubberized padding to simultaneously hold the bud in place, while also providing insulation against outside noise for the user, and insulation for people around the user form the noise he or she is hearing. Because of their extremely close proximity to the ear, intra-canal ear buds can be played at extremely low levels while still providing an enjoyable listening experience. Additionally, because they project sound directly into the ear canal and are insulated from the outside, intra-canal ear buds leak virtually no sound.
  
  

Active Noise-Reduction Headphones

• Active noise-reduction headphones project the desired sounds along with white noise.Jupiterimages/liquidlibrary/Getty Images
  
  Active noise-reduction headphones come in a variety of constructions, from over the ear headphones to intra-canal ear buds. They literally use noise to fight noise. Through a combination of white noises, they eliminate sounds that might otherwise interfere with the user's ability to hear music being played through the headphones. The only sound that active noise-reduction headphones bleed is indistinguishable white noise.