Interferometric measurements to detect resonance frequency in open tubular channels ferroelectrets - Mazulquim, Daniel Baladelli; Altafim, Ruy Alberto Pisani; Basso, Heitor Cury; Altafim, Ruy Alberto Corrêa; Gonçalves Neto, Luiz (Encontro Nacional de Física da Matéria Condensada, 2010)