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A sonometer is an apparatus made of a hollow box having two holes. A string is attached to it by which the transverse vibrations of strings can be studied. It is also called the monochord because it often has only one string. On the wooden rectangular box are two fixed bridges, near the ends, and at one end is a pulley. A string,wire is fastened at one end, run over the bridges and the pulley, and attached to a weight holder hanging below the pulley. Weights can be added to the holder to produce tension in the wire, and a third, movable bridge, can string # The reciprocal of the square root of the linear density of the string, # The reciprocal of the length of wire of sonometer i.e. where f=frequency l=first resonating length T=tension A sonometer is a diagnostic instrument used to measure the tension, frequency or density of vibrations. They are used in medical settings to test both hearing and bone density. A sonometer, or audiometer, is used to determine hearing sensitivity, while a clinical bone sonometer measures bone density to help determine such conditions as the risk of osteoporosis. In audiology, the device is used to test for hearing loss and other disorders of the ear. The audiometer measures the ability to hear sounds at frequencies normally detectable by the human ear. Several test are usually conducted using the audiometer which will then be used to assess hearing ability. Results typically are recorded on a chart known as an audiogram. A clinical bone sonometer, approved for use in the United States by the Food and Drug Administration in 1998, is a device which tests for the risk of bone fractures associated with osteoporosis. This test, called an ultrasound bone densitometry screening, is not typically used for diagnostic purposes; it is generally used as a risk assessment tool. Testing is often recommended for those whose personal history and lifestyle choices indicate a possible high risk for osteoporosis. Testing is usually conducted by an orthopedist, rheumatologist or neurologist specializing in the treatment of osteoporosis. The patient simply places his or her heel in the sonometer, and it is then scanned using ultrasound to determine bone density. This is a fast and low-cost procedure generally lasting 30 seconds or less. Results typically are available immediately following the procedure. Two score results are possible: a T-score, which compares a patient's scan against that of a young person of the same gender; and a Z-score, which compares the scan against someone of similar age, weight and gender. The T-scores results are used to assess the risk of osteoporosis. A score above -1 indicates a low risk for osteoporosis; below -1 to -2.5 indicates a risk of developing osteoporosis; and a score below 2.5 indicates more intensive testing should be performed and that osteoporosis is likely present. The Z-score reports how much bone the patient has as compared to others his age. If this number is high or low, further testing may be ordered. Women in general, specifically those older than the age of 65, are at increased risk of developing osteoporosis. Other high risk groups include the elderly, those with a family history of osteoporosis or a personal history of bone fractures and those of Caucasian, Asian and Latino descent. It is vitally important for such groups to be aware of changes in bone density. Osteoporosis is a common problem that can be quickly and simply diagnosed through the use of a clinical bone sonometer. By discovering osteoporosis in its early stages and taking steps to avoid its progression, serious consequences associated with this debilitating condition may be avoided in later years. m=mass per unit length 抄文引用元・出典: フリー百科事典『 ウィキペディア（Wikipedia）』 ■ウィキペディアで「Sonometer」の詳細全文を読む スポンサード リンク
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