68 



ANALOGIES 



way the attenuation in the mechanical system of Fig. 4.75 will be greater 

 as the sliding resistance is made larger. The acoustical system of Fig. 4.7C 

 shows a pipe line with a system of slits in series with the line. The slits 

 form an acoustic resistance. See Sec. 5.4. The attenuation in this sys- 

 tem will increase as the acoustic resistance is made larger. 



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K 



MECHANICAL 





L 



ACOUSTICAL 



Fig. 4.7. A — an electrical resistance in series with a line. The mechanical and acoustical 

 equivalents are shown in B and C. D an electrical resistance in shunt with a line. The 

 mechanical and electrical equivalents are shown in E and F. A " T " and " tt " electrical 

 resistance network are shown in G and J. The mechanical and acoustical equivalents 

 are shown in H, I, K and L. 



K. Resistance in Shunt with a Line and the Mechanical and Acoustical 

 Equivalents. — Figure 4.7D shows a resistance in shunt with a line. The 

 attenuation in this case will be greater as the resistance is made smaller. 

 In the same way the attenuation in the mechanical system of Fig. 4.7£ 

 will be greater as the sliding resistance is made smaller. In the acoustical 



