title: Perturbation Measurements on the Degree of Naturalness of Synthesized Vowels.
abstract: OBJECTIVE
  To determine the impact of jitter and shimmer on the degree of naturalness perception of synthesized vowels produced by acoustical simulation with glottal pulses (GP) and with solid model of the vocal tract (SMVT).
  
  
  METHODS
  Prospective study.
  
  
  METHODS
  Synthesized vowels were produced in three steps: 1. Eighty GP were developed (20 with jitter, 20 with shimmer, 20 with jitter+shimmer, 20 without perturbation); 2. A SMVT was produced based on magnetic resonance imaging (MRI) from a woman during phonation-/ε/ and using rapid prototyping technology; 3. Acoustic simulations were performed to obtain eighty synthesized vowels-/ε /. Two experiments were performed. First Experiment: three judges rated 120 vowels (20 humans+80 synthesized+20% repetition) as "human" or "synthesized". Second Experiment: twenty PowerPoint slide sequences were created. Each slide had 4 synthesized vowels produced with the four perturbation condition. Evaluators were asked to rate the vowels from the most natural to the most artificial.
  
  
  RESULTS
  First Experiment: all the human vowels were classified as human; 27 out of eighty synthesized vowels were rated as human, 15 of those were produced with jitter+shimmer, 10 with jitter, 2 without perturbation and none with shimmer. Second Experiment: Vowels produced with jitter+shimmer were considered as the most natural. Vowels with shimmer and without perturbation were considered as the most artificial.
  
  
  CONCLUSIONS
  The association of jitter and shimmer increased the degree of naturalness of synthesized vowels. Acoustic simulations performed with GP and using SMVT demonstrated a possible method to test the effect of the perturbation measurements on synthesized voices.
authors: Department of Otorhinolaryngology, Hospital das Clínicas da Faculdade de Medicina da Universidade de São Paulo, São Paulo, Brazil. Electronic address: r.yamasaki@uol.com.br.
authors: Rosiane
authors: R
authors: Yamasaki
authors: Department of Electrical Engineering, Universidade de São Paulo-São Carlos, Brazil.
authors: Arlindo
authors: A
authors: Montagnoli
authors: Department of Otorhinolaryngology, Hospital das Clínicas da Faculdade de Medicina da Universidade de São Paulo, São Paulo, Brazil.
authors: Emi Z
authors: EZ
authors: Murano
authors: Department of Radiology, InRad, Hospital das Clínicas da Faculdade de Medicina da Universidade de São Paulo, Brazil.
authors: Eloisa
authors: E
authors: Gebrim
authors: Department of Otorhinolaryngology, Hospital das Clínicas da Faculdade de Medicina da Universidade de São Paulo, São Paulo, Brazil.
authors: Adriana
authors: A
authors: Hachiya
authors: Division of Tridimensional Technologies, Centro de Tecnologia da Informação Renato Archer, Campinas, Brazil.
authors: Jorge Vicente
authors: JV
authors: Lopes da Silva
authors: Department of Speech-Language Pathology and Audiology-Universidade Federal de São Paulo-UNIFESP; Centro de Estudos da Voz-CEV, São Paulo, Brazil.
authors: Mara
authors: M
authors: Behlau
authors: Department of Otorhinolaryngology, Hospital das Clínicas da Faculdade de Medicina da Universidade de São Paulo, São Paulo, Brazil.
authors: Domingos
authors: D
authors: Tsuji
mesh_terms: D000161:Acoustic Stimulation; D000162:Acoustics; D000328:Adult; D055154:Dysphonia / Q000503:physiopathology; D005260:Female; D005931:Glottis / Q000000981:diagnostic imaging / Q000502:physiology*; D006801:Humans; D007600:Judgment; D008279:Magnetic Resonance Imaging; D008875:Middle Aged; D008953:Models, Anatomic; D010699:Phonation; D011446:Prospective Studies; D012815:Signal Processing, Computer-Assisted; D013061:Speech Acoustics; D013065:Speech Intelligibility; D013067:Speech Perception; D013068:Speech Production Measurement; D014833:Voice Quality; D055815:Young Adult
keywords: Acoustical measurements; Auditory-perceptual evaluation; Naturalness perception; Synthesized voices; Vocal tract model