Beyond stereo sound-stage requirements, a linear phase response helps impulse response remain true to source without encountering "smearing". An unqualified reference to a "monitor" often refers to a "near-field" (compact or close-field) design. This is a speaker small enough to sit on a stand or desk in proximity to the listener, so that most of the sound that the listener hears is coming directly from the speaker, rather than reflecting off of walls and ceilings (and thus picking up coloration and reverberation from the room). Monitor speakers may include more than one type of driver (e.g., a tweeter and a woofer) or, for monitoring low-frequency sounds, such as bass drum, additional subwoofer cabinets may be used.