Perturbation Measurements on the Degree of Naturalness of Synthesized Vowels - Yamasaki, Rosiane; Montagnolli, Arlindo; Murano, Emi; Gebrim, Eloisa; Hachiya, Adriana; Silva, Jorge Vicente Lopes da; Behlau, Mara; Tsuji, Domingos (Journal of voice, 2017)