Summary: Objective: The aim of this study was to identify the effects of objective laryngopharyngeal reflux (LPR) on the acoustic parameters of patients by comparing their voice samples with that of control subjects. Study Design: Prospective study in two tertiary reference hospitals. Methods: 48 consecutive patients with symptoms related to LPR and 64 control subjects were included in the study. Suspected LPR patients underwent a 24-hour ambulatory pH monitoring, and 25 (52%) of them were shown to have objective LPR. Acoustical evaluation results of objective LPR patients were compared with that of symptomatic LPR patients and control subjects. Results: All frequency perturbation values obtained from objective and symptomatic LPR patients were higher than the control subjects (P < 0.01). Mean fundamental frequency, amplitude perturbation measures, and noise-to-harmonics ratio were not significantly different between groups. Conclusion: LPR patients have significantly different frequency perturbation values than control subjects. © 2007 The Voice Foundation.