An iOS-based Cepstral Peak Prominence Application: Feasibility for Patient Practice of Resonant Voice

Patients participating in voice therapy often express difficulty replicating therapy targets during their independent home practice. To assist patients, an iOS-based app was developed that calculates and displays cepstral peak prominence (CPP) values for patient self-monitoring of voice quality. The purpose of this study was to investigate the usability (ie ease of use) and utility (ie helpfulness) of this app in patient practice of resonant voice, and its effect on self-efficacy for practice.

This study used mixed methods including repeated measures, survey, and semi-structured interview.

A total of 14 individuals undergoing voice therapy for a variety of voice disorders produced sustained phonation and connected speech tasks in three sequential conditions: habitual voice quality, resonant voice quality achieved without clinician assistance, and resonant voice quality achieved in interaction with the CPP app. For both tasks, CPP values were significantly and progressively higher in subsequent conditions, indicating utility of mobile CPP to differentiate habitual voice quality from resonant voice production. The participants found the app easy to use as indicated by high System Usability Scale ratings, and rated self-efficacy for practice with the app significantly higher than for unassisted practice. The interviews suggested that the participants found numeric CPP feedback helpful in self-evaluating voice quality, and thought it was "fun" to use the app.

CPP information provided on a mobile app has potential to assist and motivate patients in the achievement of resonant voice production.