Arthur Conan Doyle once described Sherlock Holmes plucking his violin for a fly trapped under an upturned tumbler. Holmes's experiment, to observe effects of sound on a living organism, has a powerful analogy in modern world. We are all flies, trapped among noisy resonances of industrialized society. And whether Holmes understood or only suspected it, sound does have an effect on living creatures. Like a drug that produces measurable effects when it enters body, noise is being found to induce physiological changes that are suspected of having a relation to disease. Noise is a stress, an environmental pollutant, an insult, says Dr. Chauncey Leake of University of California Medical Center at San Francisco. affects nervous, endocrine and reproductive systems. It may damage unborn children. According to Dr. Bruce Welch of Friends of Psychiatric Research in Baltimore, physiological effects of sound are measurable at as low as 70 decibels. They are all-pervasive, most threatening to young and yet difficult to spell out in man because problems arise from long-term, chronic exposure. Dr. Welch was chairman of a three-day symposium on physiological effects of sound at recent meeting of American Association for Advancement of Science in Boston. Says Dr. Samuel Rosen, Any loud noise, whether we like it or not, constricts blood Eventually, this could cause permanent damage. In addition to constricted vessels, says Dr. Rosen, a consulting physician at New York Eye and Ear Infirmary and Mount Sinai School of Medicine, there are other physiological reactions to noise: The skin pales, pupils dilate, eyes close and voluntary and involuntary muscles tense. Gastric secretions diminish and adrenalin is suddenly injected into blood stream. These changes, says Dr. Rosen, occur via vegetative nervous system, which plays a role in regulating changing caliber of blood vessels. Constriction occurs irrespective of whether an individual likes or dislikes a given noise. And it occurs regardless of whether a person has been exposed to that sound in past. However, severity of response appears to be clearly related to some degree to prior exposure and to an individual's general state of health and life style. Dr. Rosen and his colleagues have conducted comparative studies on effects of noise on urban dwellers in German city of Dortmund, on New Yorkers and on primitive Mabaans, an African tribe living in southeast Sudan. The urbanites came from an environment in which loud noise is commonplace. Their diets were rich in meat, butter and other animal fats. Coronary disease and hypertension are not uncommon among them. The Mabaans, on other hand, live in virtual silence, are mainly vegetarians and rarely, if ever, have high blood pressure. When exposed to noise at 90 and 95 decibels, noise level of a heavy truck, blood vessels constricted both in primitive tribesmen and individuals from industrial societies. Among tribesmen, however, constriction and relaxation of vessels were rapid, showing both quick response to and quick recovery from stress of sound. Among Westerners, vessels remained constricted for longer periods, indicating a lesser degree of elasticity in their blood vessels and a diminished capacity to recover from effects of noise. If there is already present somatic disease like atherosclerosis or coronary heart disease, continued noise exposure could endanger health and aggravate pathology by adding insult to injury, Dr. Rosen suggests. Noise, in experimental animals at least, also affects kidney function through its action on hormones. In 1964, Australian pharmacologist Dr. Mary F. Lockett was conducting tests on endocrine activity in rats when a violent thunderstorm occurred in Perth. next morning, she recounts, the animals were badly out of salt and water balance. Subsequently, she exposed rats to recorded thunderclaps of 100 decibels at a low frequency of 150 cycles per second. The noise stimulated release of a hormone, oxytocin, from pituitary gland. Oxytocin, in turn, stimulated kidney, resulting in enhanced excretion of salt and water. High-frequency sounds had another effect. They stimulated adrenalin secretion up to 20 times normal levels and caused water retention, rather than excretion, because adrenalin inhibits synthesis of antidiuretic hormone, which inhibits excretion of fluids. Dr. John L. Fuller of Jackson Laboratories in Bar Harbor, Me., sees animals' response to noise as a valuable laboratory model for studying biology of stress and chemistry of brain as it affects nervous system. With Dr. Robert L. Collins, he has been looking at sound-induced seizures in inbred strains of mice. The genetic makeup of a mouse influences its response to noise. Not all strains will convulse when stimulated by sound, Dr. Fuller Decibels