On the Second Spectral Peak of Front Vowels: a Perceptual Study of the Role of the Second and Third Formants

A set of vowel stimuli with different values of mean and separation of the second and third formant frequencies were synthesized by means of series-connected resonant circuits, and formal listening tests were conducted where Swedish subjects identified each stimulus as one of three syllables consisting of a long close front vowel, /i : /, /y : /, or /u :/. The commonly accepted notion of representing the vowel quality in a two-dimensional space is criticized in view of the experimental result. Some supplemental tests of the ABX-comparison type have been conducted, and results concerning the perceptual acuity in regard to slight shifts of the formant conditions are also reported.