62 MATTER WAVES: SOUND AND ULTRASOUND 



being gained on animals, principally guinea pigs, rats, and mice. The in- 

 vestigations have not been extensive enough to denote anything other than 

 generalities. However, at 165 db, 500 to 400,000 cps, on guinea pigs, 

 pathological changes occur in both the inner and middle ear; lesions appear 

 in the organ of Corti, and it is ruptured from the basilar membrane. Hemor- 

 rhages start where the malleus meets with the eardrum. Convulsions often 

 result. The skin becomes blistered and reddened. Death is hastened by the 

 damage. 



TABLE 3-2. Effects of High-Intensity Sound on Man* 



Frequency (cps) Level (db) Effect 



stimulation of receptors in skin 

 mild warming of body surfaces 

 nausea, vomiting, dizziness; interference with touch 



and muscle sense 

 significant changes in pulse rate 

 pain in middle ear 

 changes in muscle tone; increase in tendon reflexes; 



incoordination 

 minor permanent damage if prolonged 

 major permanent damage in short time 

 vibration of muscles in arms and legs 

 resonance in mouth, nasal cavities, and sinuses 



♦Collected by Neeley, K. K., "Noise — Some Implications for Aviation," Can. Aeronaut. J., 3, 312 (1957). 



SONIC AND ULTRASONIC THERAPY 



Certain uses have already been demonstrated; others await discovery, for 

 the technique is very new to medicine. The following applications are al- 

 ready well known in principle, and are now being introduced in practice very 

 cautiously — for the early 1950's saw the period of novelty wax strong, and 

 then wane into a hard reappraisal in the mid-50's; and one now observes the 

 gradual emergence of the place of vibrations in the medical arsenal. Details 

 can be found in the reviews of two masters of the subject, R. F. Herrick 10 and 

 W.J. Fry 1 and in the book edited by E. Kelly. 2 



Present Applications 



(1) Subcutaneous lesions can be located by ultra high-frequency matter 

 waves. They focus well at 1 Mc, and penetrate to a useful depth. The depth 

 of penetration is a function of the power of the source. Since reflection of 

 matter waves is greater the higher the density of the medium, tumors can be 

 distinguished from normal tissue at a location deep below the surface. 



