title: Transfer function of Brazilian Portuguese oral vowels: a comparative acoustic analysis.
abstract: The vocal tract transfers its characteristics onto the sounds produced at the glottis, depending on its tridimensional configuration.
  
  
  OBJECTIVE
  this study aims to determine which of the seven oral vowels in Brazilian Portuguese is acoustically less impacted by changes to the vocal tract.
  
  
  METHODS
  this is a cross-sectional prospective study. Twenty-three males and 23 females with ages ranging between 20 and 45 years (mean values of 28.95 and 29.79 years respectively) were enrolled in the study; none had voice complaints and their voices were normal under perceptive-auditory evaluation. Three-hundred and twenty-two sustained vocal emissions were digitized and acoustically analyzed by three computer programs combined. Results were compared against the distribution of resonance frequencies in a straight tube with one end sealed.
  
  
  RESULTS
  statistical analysis showed that vowel /epsilon/ was significantly different when compared to the other vowels, with higher mean harmonic values and lower standard deviation for both genders.
  
  
  CONCLUSIONS
  in Brazilian Portuguese, vowel /epsilon/ is less impacted by changes to the vocal tract and is significantly less attenuated in both genders. The inclusion of this vowel in voice assessment standard protocols may contribute to improve the quality of the information obtained as a result of quantitative spectrographic and acoustic tests.
authors.affiliation: Federal University of São Paulo, São Paulo, SP, Brazil.
authors.forename: Maria Inês Rebelo
authors.initials: MI
authors.lastname: Gonçalves
authors.forename: Paulo Augusto de Lima
authors.initials: PA
authors.lastname: Pontes
authors.forename: Vanessa Pedrosa
authors.initials: VP
authors.lastname: Vieira
authors.forename: Antônio Augusto de Lima
authors.initials: AA
authors.lastname: Pontes
authors.forename: Daniella
authors.initials: D
authors.lastname: Curcio
authors.forename: Noemi Grigoletto
authors.initials: NG
authors.lastname: De Biase
mesh_terms: D000328:Adult; D001938:Brazil; D003430:Cross-Sectional Studies; D005260:Female; D006801:Humans; D008297:Male; D008875:Middle Aged; D010700:Phonetics; D011446:Prospective Studies; D013018:Sound Spectrography; D013061:Speech Acoustics; D013067:Speech Perception / Q000502:physiology*; D055815:Young Adult