Tehran University of Medical Sciences Auditory and Vestibular Research 2423-480X 22 3 2017 07 31 52 62 Abolfazl Salehi Department of Speech therapy, University of Social Welfare and Rehabilitation, Tehran, Iran Farzad Izadi Ear, Nose, Throat, Head & Neck Research Center, Hazrate Rassul-e-Akram Hospital, Tehran University of Medical Sciences, Tehran, Iran Laya Gholami Tehrani Department of Speech therapy, University of Social Welfare and Rehabilitation, Tehran, Iran Mehdi Rahgozar Department of Biostatistics, University of Social Welfare and Rehabilitation Sciences, Tehran, Iran 2017 05 29 Background and Aim: An imbalance between phonatory subsystems may lead to disturbing phonatory muscular balance and consequently voice disorders. Based on theoretical issues, criterionbased laryngeal manual therapy, as a novel treatment method which is supported by classical laryngealmanual therapy, can improve voice quality using manual maneuvers combined with phonatory tasks. The present study aimed to report the treating effects of this method on hyperfunctional voice disorders. Methods: Twenty adult participants with hyperfunctional voice disorders by the least three months history of voice disorder were selected. The participant’s voices were assessed multidimensionally using acoustic, audio-pecreptual and stroboscopic assessments before and after treatment. Results: There were a decrease in jitter (p=0.003) and shimmer (p<0.001) and also, increase in harmonic-to-noise ratio (HNR) (p<0.001) of vowel /a/ after treatment. Besides, there was an increase in harmony to noise ratio (p=0.009) and decrease in jitter (p=0.020) of vowel /i/, too. There were not significant changes in shimmer amount of vowel /i/ (p=0.170) after treatment. There were highly significant changes in all aspects of audio-perceptual (p<0.001) and videostroboscopic (p<0.001) parameters. Conclusion: Using voice-based laryngeal manual therapy can be a treatment method in handling hyperfunctional voice disorders https://avr.tums.ac.ir/index.php/avr/article/view/294