Subwoofer headphones are a type of circumaural headphones that is capable of producing very low frequency sounds. Unlike normal headphones, these devices can be very well suited to playing music that relies heavily on bass. This is typically accomplished by including vibration speakers in addition to the traditional magnetic loudspeakers. The frequencies that these vibration speakers are capable of producing can vary, and there is often some method of adjusting the bass levels of subwoofer headphones so that they can be individually tuned to the personal preferences of each listener. Some high end headphones are able to produce low frequencies well without an additional subwoofer, though they are typically more expensive.
Headphones are essentially small loudspeakers that can be worn on, over, or in the ears. Since the size of a speaker typically dictates the frequencies that it can produce well, speakers small enough to be worn on a listener's head are not typically suited to producing bass. Some high-end headphones have excellent bass reproduction, but they are typically very expensive. A more affordable option is adding an additional speaker to circumvent the size restrictions. This can allow subwoofer headphones to produce quality bass sounds when listening to certain kinds of music, watching movies, or playing video games.
Most headphones rely on the power of an audio signal to drive the loudspeakers, but portable music devices and many other audio sources lack the necessary power to drive the additional speakers found in subwoofer headphones. In order to power these additional vibration speakers, some type of amplification device is typically required. This type of power amplifier is sometimes included right in the subwoofer headphones, or in-line with the audio cable. Since the amplifier requires electricity to operate, these headphones are typically battery powered. When the battery is removed, or the power is turned off, the sound reproduction typically suffers and the headphones may sound tinny or hollow.
In addition to a powered amplifier, some subwoofer headphones also include an in-line line control for the bass boost function. These types of controls can be used to tune the bass levels depending on what is being listened to. Different types of music each have unique bass profiles, so this type of control can ensure an optimum listening experience regardless of the audio source. These controls can also be useful when watching television and movies, or playing video games. Each of these activities can also have its own levels of base that require different settings in order to sound pleasing.