The intense and prolonged use of the voice is the leading cause of vocal fatigue and, in the most severe cases, of genuine voice disorders, especially for professionals — teachers, singers, call-centre operators — whose voice is their main working tool. Conventional clinical assessment, being episodic and largely subjective, cannot capture real day-to-day voice use; this is why vocal dosimetry, the continuous, ambulatory monitoring of phonatory activity, has become established. Existing systems rely on an accelerometer or a contact microphone but tend to be expensive, and limited in the variables measured, motivating portable, low-cost tools that provide an objective estimate of vocal fatigue.