A near-ultrasonic pure tone of 15,570 Herz generated by flyback transformers in computer and video display terminal (VDT) monitors may cause severe non-specific irritation or stress disease in operators. Women hear higher frequency sounds than men and are twice as sensitive to "too loud" noise. Pure tones at high frequencies are more annoying than broadband noise at the same level. Because hormonal levels influence sensitivity to high frequency sound in both men and women, stress symptoms may be intermittent, but all who hear the pure tone are affected. Meaningless noise may induce physiological changes in stroke volume of the heart, pulse amplitude, dilatation of the pupil, the ability to quickly change focus of the eyes or move the eyes through certain angles. A survey of 38 students in two college classes using the same classroom equipped with 21 desktop computers revealed that 15 students (12 of them women) could hear the high-pitched sound. Nearly all 26 female students reported stress decreased noticeably shortly after computer monitors were turned off. Two sets of acoustical measurements were made in this classroom, one by an audiologist and one by an acoustical engineer. Both tests indicated a distinctive pure-tone sound at the 16 kHz frequency. Past studies of VDT health effects have not considered pure-tone sound or gender effects as possible causes of stress and stress disease symptoms in computerized workplaces or classrooms. (One table of data and 47 notes are included.) (SR)