8 BELL SYSTEM TECHXICAL JOURNAL 



earlier, the observers in these tests were considerably more experienced and 

 critical than average radio audiences. The program material tested was 

 representative of most of the programs on the air, but different results would 

 be obtained with material markedty different in nature. This would prob- 

 ably be particularly true of selected sound effects. Secondly, it should not 

 be forgotten that the results are based onty on the ability of the ear to detect 

 the changes, with no weighting for factors such as aesthetic values or per- 



Table I 



Musical Instruments 



1. Flute 



2. Snare Drum 



3. Violin 



4. Soprano Saxophone 



5. Oboe 



6. 14 in. Cymbals. . . . 



7. Bass Clarinet 



9. Piccolo 



9. Bassoon 



10. Cello 



11. Bass Saxophone. . . 



12. Clarinet 



13. Trumpet 



14. Bass Viol 



15. Trombone 



16. Bass Tuba 



17. French Horn 



18. Piano 



19. Bass Drum 



20. Timpani 



Speech 



Male 



Female 



Sound Effects 



Footsteps 



Handclapping 



Key Jingling 



Upper Frequency Limit 



Versus Unrestricted Band, 



Corresponding to One 



Liminal Unit 



13,500 cycles 



13,000 



13,000 



12,700 



12,700 



12,000 



10,500 



10,200 



10,000 



9,800 



8,600 



8,500 



8,300 



7.800 



7,200 



6,300 



6,100 



5,600 



4,300 



3,500 



7,300 

 9,200 



12,000 

 15,000 

 15,000 



sonal preferences, or for the effects of room noise and other factors present 

 in the practical case. Thirdly, it should be appreciated that comparison 

 tests such as these are very sensitive tests, showing up differences that could 

 not be detected under usual home listening conditions. 



It is of interest to compare the above results with previously published 

 data. In a paper "Audible Frequency Ranges of Music, Speech and Noise, "^ 

 W. B. Snow gave data for 20 musical instruments, certain noises, and 



1 Jour. Acous. Soc. Amer., July 1931; Bell Sys. Tech. Jour., Oct. 1931. 



