RESUMEN
INTRODUCTION: A large number of people around the world struggle daily to become free of their addiction to illegal psychoactive substances. In order to create an atmosphere of improved supervision, established communication and improved quality of life for drug addicts, centers have been set up to provide methadone as a substitute. OBJECTIVE: The aim of the research was to assess the vocal features of drug addicts on methadone therapy via subjective and objective parameters, to ascertain if vocal damage has occurred and to determine whether subjective and objective acoustic vocal parameters are related, and how. METHODS: The research included 34 adults of both genders who were undergoing methadone treatment. A subjective vocal evaluation assessed voice pitch and clarity, while the subjective acoustic analysis utilized the Roughness-Breathiness-Hoarseness scale of roughness-breathiness-hoarseness. Objective acoustic analysis was conducted after recording and analyzing an uninterrupted vocal /a/ of at least three seconds duration, using the "GllotisController" software. RESULTS: The subjective acoustic analysis using the Roughness-Breathiness-Hoarseness scale showed pathological values in 52.9% male and 47% female participants. The average values of the roughness-breathiness-hoarseness for the entire sample were 0.91, 0.38 and 0.50, respectively. Lower roughness was associated with a higher fundamental frequency (f0) and lower jitter and shimmer values (p<0.05). There was a statistically significant correlation between breathiness, jitter (p<0.01) and shimmer (p<0.05), and between hoarseness and jitter (p<0.01). CONCLUSION: A statistically significant correlation was found between the two subjective vocal assessments, voice clarity and pitch, and Roughness-Breathiness-Hoarseness scale, and the parameters of the objective acoustic vocal assessment.