Perceptual confusions of high-pitched sung vowels

Questions exist as to the intelligibility of vowels sung at extremely high fundamental frequencies and, especially, when the fundamental frequency (F- 0) produced is above the region where the first vowel formant (F-1) would n ormally occur. Can such vowels be correctly identified and, if so, does con text provide the necessary information or are acoustical elements also oper ative? To this end, 18 professional singers (5 males and 13 females) were r ecorded when singing 3 isolated vowels at high and low pitches at both loud and soft levels. Aural-perceptual studies employing four types of auditors were carried out to determine the identity of these vowels, and the nature of the confusions with other vowels. Subsequent acoustical analysis focuse d on the actual fundamental frequencies sung plus those defining the first 2 vowel formants. It was found that F-0 change had a profound effect on vow el perception; one of the more important observations was that the target t ended to shift toward vowels with an F-1 just above the sung frequency.