1184 THE BELL SYSTEM TECHNICAL JOURNAL, SEPTEMBER, 1953 





Fig. 8 — Correlatogram of single-frequency wave and random noise. 



one noise input because of the idle interval during which no signal is 

 supplied by the delay line is a source of change in the direct current which 

 is partially transmitted through the product amplifier to give a biased 

 integrated value and hence an unequal treatment of positive and negative 

 correlation. Effects of this sort would be particularly noticeable when the 

 noise is large relative to the sinusoidal component. 



Fig. 9 shows a sample correlatogram of the sentence ''He beats his 

 head against the posts." spoken by G. E. Peterson. The locations of the 

 sounds were marked on the tape by observation during an audio playback 

 and from these marks the corresponding positions on the correlatogram 

 were found. The lower legend gives the ordinary English letters and 

 the upper the symbols of the international phonetic alphabet. The 

 characteristic frequency indicated by the vowel sounds is of the order 

 of 600 cps, which coincides very well with the first formant frequency 

 of the speaker's voice. It is a characteristic of this method that the 

 pattern is dominated by the largest component present. To show the 

 higher formants, which have weaker amplitudes, it would be necessary 



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Fig. 9 — Correlatogram of speech sentence. 



