2. Materials and Methods
neurogenic voice disorders
This study was designed as a pilot ‘proof-of-concept’ study and met the requirements for clinical trials specified by the National Institutes of Health [A total of 33 participants were recruited for the study and met the following inclusion criteria: adults (>18 years) with non-disordered/normophonic voice, non-smokers, hearing levels within functional limits, and iPhone users. Hearing within functional limits was defined as the participant’s ability to follow voice therapy instructions, imitate vocal exercises, and incorporate feedback provided during experimental tasks. iPhone users were defined as participants in possession of a mobile phone supported by iOS. The presence of vocal fold lesions or neurogenic voice disorders identified by endoscopic visualization and abnormal scores on auditory-perceptual evaluation constituted exclusion from the study. Additionally, participants with prior experience with Vocal Function Exercises were also excluded from the study. Participants who were non-treatment-seeking with normophonic voices were chosen, as this was the beta-testing phase of the smartphone app.