274 The Symballophone 



one ear. Among medical students, about lo per cent have auditory defects 

 which preclude any practical use of the symballophone. To some of them the 

 binaural stethoscope is of no more value than the original monaural stetho- 

 scope would be. Older physicians whose auditory functions are failing do not 

 derive additional information from the use of the symballophone. 



Summary 



The symballophone, an improved double stethoscope for lateralization and 

 comparison of sounds, has been described. A brief historical sketch has been 

 given of the evolution of the stethoscope, and previous types of lateralizing 

 stethoscopes have been mentioned. The psychological and clinical studies 

 which led to the perfection of the symballophone have been discussed. The 

 application of the symballophone to medical practice has advanced our inter- 

 est in the art of auscultation and our knowledge of the fundamental principles 

 involved in the moving structures in which sounds are produced. The symbal- 

 lophone should replace the ordinary binaural stethoscope for all clinical 



purposes. 



REFERENCES 



1. Muralt, L. V.: Btrge. z. Klin. d. Tuberk. i6: 121, 1910. 



2. Froschels, E.: Med. Klin. 30:1099, 1934. 



3. Nicolai, L.: Klin. Wchnschr. 15:91, 1936. 



4. Hantschmann, L., and Nicolai, L.: Klin Wchnschr. 15:92, 1936. 



5. Hawthorne, C. O.: Irish Jl. Med. Sci. (7[i.e., 6]) 1935:49. 



6. Alison, S. S.: Med. Times & Gaz. (n.s.) 19:7, 28, 1859. 



7. Kerr, W. J.; Althausen, T. L.; Bassett, A. M., and Goldman, M. J.: Amer. Heart Jl. 14:594, 



1937- 



8. Kerr, W. J.; Althausen, T. L.; Bassett, A. M., and Goldman, M. J.: Trns. Assn. Amer-Physns. 



52:92. 1937- 



9. Kerr, W. J.: West. Jl. Surg., Obstet. & Gynecol. 49:632, 1941. 



