BACKGROUND: In this study we compared the perceived diameter of the vocal tract's oropharyngeal part with the diameter that was determined endoscopically. METHODS: 28 singers (13 male, 15 female) were examined with transnasal fiberscopic pharyngoscopy while singing the vowels /a/, /i/ and /u/ in 4 different timbres (normal, opened, covered, dumpled) and 3 different pitches (chest/modal register, subjective comfortable pitch for singing, head/falsetto register). The tactile-kinesthetic and auditive rating of the singers, the auditive rating of a singing teacher and the visual-endoscopic analysis of three laryngologists were compared. RESULTS: The tactile-kinesthetic and auditory self-perception of the singers was quite different from the auditive perception of a singing teacher and visual endoscopic findings of the laryngologists. The singers had the impression that the different singing timbres (normal, opened, covered, dumpled) influence oropharyngeal vocal tract space during singing. They judged the vowel itself and the pitch as having very little influence. Based on his auditory perception, the singing teacher also rated that the timbre plays an important role for the oropharyngeal vocal tract space but he found vowels to be the parameter with the greatest impact. Via visual endoscopic examination we found that, among the three parameters (vowel, timbre, pitch), the different vowels are most influential on the oropharyngeal vocal tract space. Analysis of video sequences revealed that pitch and timbre are less important. CONCLUSION: Subjective tactile-kinesthetic and auditory perception of the singers differs from auditory perception of the singing teacher as well as from endoscopic findings. The endoscopically determined oropharyngeal vocal tract space during singing the vowels /i/ or /u/ tends to be larger compared to the oropharyngeal vocal tract space while singing the vowel /a/.
