A type of headphone design where the headphone forms some type of a seal around (or in) the ear. The purpose of closed ear headphone designs (in contrast with open air designs) is to provide isolation between the headphone signal and the outside world. This benefits users who are trying to monitor signals in loud environments. They also help keep headphone signals from leaking out and possibly corrupting a recording by leaking into mics, etc. Closed ear designs are usually not as comfortable as the better open air designs, and some users believe they don’t generally sound as good, but they are a necessity for most recording studios.