A psychoacoustic effect that conveys proximity to the listener. The perceived volume of a sound and its frequency content create presence. Boosting the frequencies between 4khz and 6khz will increase the presence effect. Conversely, reducing the frequencies around 5khz will cause the sound object to appear psychoacoustically more distant (or, cause them to lose presence and gain absence.)
The human voice's sibilants are localized in this 5khz frequency, and in natural listening situations the greater the distance between the source voice and the listener, the less audible sibilants are. In vocal sounds specifically, presence and the resulting vocal intimacy can also be attained with compression and close microphones. The compression and physical distance from mouth to microphone will raise the volume of even the quietest of mouth sounds and cause the listener to feel as if the voice were right next to their ear.