The set of nine nondiphthong vowels of American English were synthesized using the male formant values from Peterson and Barney [J. Acoust. Soc. Am. 24, 175–184 (1952)]. These vowels were produced in three conditions of the fundamental frequency: (1) average 135 Hz, (2) low 100 Hz, and (3) high 250 Hz. In forced-choice testing, subjects identified vowels in the average and low condition of the F0 with greater accuracy than the high F0 vowels. A second experiment was conducted using the female formant frequency values from Peterson and Barney and the same conditions of F0. Subjects still performed better on the low and average condition of the F0 for these vowels. These results suggest that the human formant frequency extractor is aided by the denser spectral sampling of the transfer function by a lower fundamental. The pattern of vowel errors was the sense neither across F0 conditions nor across male or female formant values. The point vowels [i] and [u] were the most consistently identified across all conditions.