THF. SOUNDS OF SPEECH 607 



by chrxising from each riTord only a few such ryclt's as rcprfscnla- 

 tive and analyzing tlusi-.' If, for exarnplo, only U) cyrk-s wi-ro taken 

 at selecteil intervals from each of the KM \'o\vel records shown there 

 wouki he retiuired o\er one thousand such anaKses, and to he of value 

 these analyses should include components of fre(|uency from 100 to 

 a,(MK) cycles. For this reason a mechanical method of analysis has 

 lieen ajiplieil to clctermine from the records the average fre(iuency 

 spectra of each of the vowel and semi-vowel sounds. 



First let us consider the vowel records in a simpler and more general 

 way. Considerahle information has been obtained by inspection, using 

 such simple apparatus as a pair of compas.ses and a rule in connection 

 with the time scale on the records. The time scale greatly facilitates 

 the process; it is in most cases possible to count the number of cycles 

 of any one prominent comp>onent occurring in an interval of .01 

 second, and by doing this in \arious parts of the record, to arrive at a 

 rough average frequency for the component in question. 



In the case of the low frequency components (the fundamental and 

 the lower characteristic frequency) the procedure was to make this 

 examination at 3 points; one near the start, one near the middle, and 

 one near the end of each record. In this way the most significant 

 changes in pitch and wave form during the course of the record can be 

 brought to light, and some of the individual characteristics of the 

 speaker revealed. A statistical compilation of these results serves to 

 show certain "normal" characteristics of pitch variation, and permit 

 the detection of a certain amount of "personal bias" of the individual 

 speaker in his departure therefrom. In the examination of the low 

 frequency characteristics a note was made as to the harmonic relation 

 between the fundamental and the lower characteristic frequency; of 

 the amplitude of the lower characteristic frequency as being greater 

 or less than the amplitude of the fundamental; and of the behavior of 

 the amplitude of the lower characteristic, during the cycle of the funda- 

 mental. The amplitude of the low frequency characteristic is either 

 substantially constant during the cycle or falls away as a transient 

 vibration. 



The high frequency components are clearly shown in the records, 

 but it is more dit^lcult to determine their exact frequencies, and prac- 

 tically impossible to relate them harmonically to the fun<lamental. 

 These oscillations were counted in from four to eight locations in each 



' It is practicable, however, to obtain valuable data as to the formation of the 

 vowel sounds by analyzing separately the successive cycles at the beginning of a 

 typical vowel record. .\ study of this kind, based on these records, is lieing carried 

 out by Messrs. .N. R. French and W. Koenig of the .American Telephone and Tele- 

 graph Company. 



