APPLICATION OF ARTICULATION TESTING 369 



pressed short circuits are applied to prevent the operation of a system 

 of error counting relays, but if the wrong keys are pressed the related 

 relays act to indicate the errors. There are twelve of these relays, 

 giving a separate count of each observer's errors on each of the three 

 sounds of the test syllable. 



The relay circuits are arranged so that the same keys are used for 

 both initial and final consonants and also so that the observers are 

 prevented from getting more than one opportunity to record on each 

 sound. 



While the observers are recording, various other automatic operations 

 are going on under the control of the timing commutator. The auto- 

 matic noise measuring apparatus measures the amount of noise de- 

 livered to the observers' receivers. Shortly afterwards the telephone 

 system under test is switched so that the next sentence to be called 

 will go over it in the opposite direction from the first. Also during 

 the recording period, the first group of decoding relays is knocked down 

 and set up again as the tape moves forward to flash the next syllable 

 to the caller. 



Immediately after the recording period, a set of error totaling cir- 

 cuits counts the total number of errors made by each observer. These 

 circuits operate cumulatively, that is, errors on the next syllable will 

 be added to these, and so on until the end of the list. Another set 

 of error totaling circuits, however, acts at once to cause the page 

 printer to type the total number of errors made on each sound of the 

 syllable by all of the observers. After this the second group of de- 

 coding relays is knocked down. By this time the caller has finished 

 calling the second sentence and the cycle is repeated. 



These operations continue for 66 syllables. At the conclusion of the 

 cycle covering the last syllable the page printer under the joint control 

 of the paper tape and the timing commutator, as was pointed out 

 before, records the number of the list, the serial number of the calling, 

 a code letter A or B to denote to which of two circuits being compared 

 the data pertain, the total errors made by each observer on all sounds, 

 and the average values of speech and noise as measured at the ob- 

 servers' receivers by the automatic measuring apparatus. 



Mechanical Formulation of Testing Lists 

 The first automatic analyzer, although no longer in use, was dis- 

 tinguished by a special feature which has aroused some interest and 

 will therefore be described. 



The machine was arranged to make up the lists automatically as 

 they were needed and also to censor the list automatically before 

 using it. 



