15G Dr. G. A. Campbell on 



recorded correctly in 59 per cent, of the cases, and the leading 

 mistake was made in 26 per cent, of the cases. Even as the 

 records stand, it will be seen that / and s are correctly re- 

 corded twice as frequently as they are interchanged with 

 each other. While these results are not directly applicable 

 to the acousticon, which is the instrument referred to by 

 Lord Rayleigh, the difference should be in favour of the 

 acousticon, for our tests were made with commercial instru- 

 ments over long commercial lines. 



As the conditions of our tests differed from those of Lord 

 Rayleigh in almost every particular, further tests, summarized 

 in Table IV., have been made which bring the conditions 

 more nearly into agreement. The number of syllables in 

 each list was here reduced to two, and the six distinct series 

 of tests included Lord Bayleigrr's test syllables five and sive ; 

 fix and six, and also fee and see ; ohm and own ; am and an ; 

 me and knee. Each list contained one hundred syllables, 

 and was varied each time it was called. The lists were called 

 over the telephone by six persons, here designated as E, 

 F, G, H, I, J ; of these I and J were young women. Four 

 telephone receivers were arranged in series, parallel at the 

 receiving station, and four persons A, B, C, D, listened 

 simultaneously and made independent records. This method 

 materially reduced the time and labour of making this set of 

 14,400 records, and it also enables ns to compare directly 

 the records of different observers with any one person calling 

 or of any one observer with different persons calling. Observer 

 E listened directly to H, I, and J, and these records are added 

 to the table. The ten persons who assisted in these tests 

 were familiar with the use of the telephone, but they had had 

 little or no practice in syllabic tests. The telephone con- 

 nexion from the talking to the listening station was made 

 through the private branch exchange of the office, and therefore 

 the length of line included was almost negligible. 



It will be seen that the records made by E for direct 

 receiving through the air were in general nearly perfect, but 

 that for " ohm " and " own " they were in some cases poorer 

 than the telephonic records. Comparison of the original records 

 for each calling of the lists shows that the distribution of mis- 

 takes was, on the whole, purely accidental, and could not be 

 traced to definite irregularities in the pronunciation ofthe lists. 



For Lord Eayleigh's syllables fix and six, five and sive, 

 about 85 per cent, of the records were correct ; haphazard 

 records would have averaged but 50 per cent, correct. In 

 one case,, F calling and D recording, a perfect record was 

 made for the " five-sive " list. 



While it is obvious that the telephone seriously distorts 

 speech- waves, nevertheless even those consonants which most 

 nearly resemble each other are not distorted sufficiently to be 

 indistinguishable. 



