Identification of Filtered Vowels
Gordon E. Peterson, Ilse Lehiste · The Journal of the Acoustical Society of America · 1959
In sustained vowels the formants are essentially fixed in frequency position, so that the various formant frequencies can be eliminated by means of high-pass and low-pass filtering. A filtering technique was employed in order to determine the relative influence of the various formant frequencies upon vowel identification. The endings were removed from the vowels by means of a gate circuit, and the vowels all had essentially the same fundamental voice frequency. Subjects trained in phonetics served as listeners for the experiment. The data show that the contributions of the various formants to vowel recognition differ with various vowels. When the high-pass filter admitted only formants above the third, vowel identification dropped below 5%. Vowel substitutions are highly predictable under certain conditions of filtering. The data thus do not support the thesis that any major section of the vowel pattern is adequate for the identification of all vowels. Rather, they indicate that certain particular aspects of each vowel pattern are primary, or may be considered as essential information bearing vowel parameters.