Design Issues for a Portable Vocal Analyzer

Abstract

The aim of this paper consists in identifying the main design specifications of a portable analyzer that allows the vocal signal of a person under monitoring to be acquired and stored. Suitable calibration procedures will be also defined for the microphone used in the portable device in order to ensure the traceability of the obtained measurements. The collected data will be used to identify voice disorders, to prevent an improper use of the voice, and to evaluate the vocal effort induced by noisy and/or reverberant environments. The vocal analyzer is based on a contact microphone worn by the person under monitoring and a portable microcontroller-based unit that hosts the conditioning circuitry, analog-to-digital converter, and storing memory. Two alternative sensors are investigated as contact microphones: an accelerometer and an electret condenser microphone. The former is expected to exhibit a negligible sensitivity to airborne effects, and the latter would provide a larger bandwidth, thus allowing parameters related to the vowel quality to be estimated. Particular attention will be paid toward traceability assurance and uncertainty estimation, and a calibration procedure for each of the estimated parameters will be proposed. In this paper, a data-acquisition-board-based setup has been used instead of a portable microcontroller unit in order to easily perform tests that allow the used microphones to be characterized and the calibration procedures for the parameters of interest to be assessed. Experimental results are reported that refer to the estimation of the parameters sound pressure level ( <i xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">SPL</i> ) and fundamental frequency ( <i xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">F</i> <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">0</sub> ).