12 



Destructive Effects of High 

 Intensity Ultrasound 



I. High Intensity Ultrasound 



Acoustic energy of sufficiently great intensity can damage living cells 

 in several ways. First, there is the nonspecific effect of heating. This 

 type of destruction results from the absorption of high intensity ultra- 

 sonic waves in the manner described in the previous chapter. There 

 are, however, two more specific types of effects which may occur. These 

 are the rupture of single cells in watery suspensions when the medium is 

 subjected to sufficiently intense sound fields, and the damage to nervous 

 tissues which is highly specific as to which cells are destroyed. 



These types of acoustic destruction are independent of hearing and can 

 probably be demonstrated at almost any frequency. Some authors have 

 suggested calling the entire spectrum from subaudible to superaudible 

 by the name sonic when hearing is not involved. However, most of these 

 destructive effects have been studied and used at frequencies above the 

 limits of human hearing. Accordingly, they are referred to as ultrasonic 

 in this text. 



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