Telephonic Intelligibility, 153 



Company begun un investigation of the distortion introduced 

 by the telephone instruments and transmission network. 

 The work has not advanced sufficiently to warrant general 

 statements as to the telephonic intelligibility of: the 5000 

 phonetic syllables employed in the English language, but 

 what has been done seems to show the order of intelligibility 

 of the consonantal sounds with some definiteness. 



For the tests which will be described the following twenty 

 syllables, each ending in long i and preceded by one of the 

 simple consonant sounds, were used : — 



bi as 



in bee 



ni as 



in knee 



chi 



Chi(le) 



Pj 



pea 



di 



de(pot), dee 



ri 



re(bus), rei 



fi 



fee 



si 



see 



gi 



G-i(zeh) 



shi 



she 



hi 



he 



ti 



tea 



ji 



gee 



thi 



the(ory) 



ki 



key 



vi 



ve(nus), vee 



li 



lee 



y'} 



5' e 



mi 



me 



zi 



ze(bra), zee. 



The list contains seventeen words and three syllables which 

 occur in compound words. According to the scientific 

 alphabet used in the Standard Dictionary, there are bul 

 twenty-four elementary English consonant sounds. All of 

 these consonant sounds are included except dh, ng, id, and 

 zh ; dh is somewhat like ///, and was similarly recorded in an 

 earlier series of tests; w was recorded correctly in 99 per 

 cent, of the cases in a set of twelve thousand records ; ng 

 and zh are not of frequent occurrence, and do not seem to be 

 used as syllables with merely long /' following. 



Ten lists of one hundred syllables each were prepared, 

 every one of which contained the twenty consonants five 

 times in a perfectly haphazard manner. All of the ten list> 

 were spoken over the telephone connexion and a record made 

 of the consonant heard. The tests were then continued, the 

 experimentors changing places. All records were made in a 

 quiet room and over quiet lines. Before this series of tot- 

 was begun the observers had made at least fifteen thousand 

 records, and had become perfectly familiar with the method 

 of test. The syllables were never repeated for any one given 

 record, and the observer always made a record however 

 uncertain he might feel as to its correctness. While the 

 sequence of the lists and of the syllables was perfectly hap- 

 hazard, the observer knew that each syllable occurred the 

 same number of times in each list of one hundred syllables. 

 This may have led in some cases of uncertainty to recording 

 a syllable merely for the reason that it did not seem to have 



