One of the most impressive physical accomplishments of the Bene Gessent sisterhood, the idiomatic terminology used to refer to the manipulation of speech to achieve complete control over the receiver, the production of extraperceptual auditory stimuli capable of implanting a message in an individual's unconscious, thus creating a com pulsion to obey Although Voice is founded on physical knowledge, only the Bene Gessent were able to exploit for practical purposes the knowledge that others possessed but did not understand PHYSICAL DESCRIPTION The production of extraperceptual auditory stimuli involves manipulation of the laryngeal musculature in a manner that generates overtones well above the 20 000 cycles per second (cps) limit for conscious reception Bene Gessent training enables adepts to control the thyro-arytenoid vocalis and cncothyroid muscles so as to intentionally regulate vocal quality in a man ner that generated specific frequencies with in the 25,000-35,000 cps range Normal phonation, caused by tension of the vocal folds to effect condensations and rarefactions of the airstream, operates within a range of 500 to 4,000 cps, with random and only partially controlled overtones up to 10,000 cps It is the combinations of overtones-along with the resonating characteristics of the pharyngeal, nasal and oral cavities that amplify specific frequencies-that account m large measure for the vocal quality thdt makes each individual s voice somewhat unique For instance, the trained singing voice owes its richness to overtones of more than ordi nary amplitude Sktllful manipulation of Voice requires generating these overtones without altering the basic pitch or loudness of the perceived voice Each individual word or phoneme requires a unique combination of perceived tones and extraperceptual frequencies This perceptual/extraperceptual ratio (specific combination of perceptual and extraperceptual frequencies) must vary ac VOICE 499 cording to the position of a phoneme within a word, be it initial, medial or terminal PSYCHOLOGICAL FUNCTION Extraperceptual stimuli trigger so-called ancommit-ted zones of the auditory cortex That effect frequently has been measured m the laboratory using high-frequency sounds from whistles and animals It also is recognized that numerous languages from Old Terra.