Design Issues for a Portable Vocal Analyzer

The aim of this work 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 micro-controller based unit that hosts 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 air-borne effects, the latter would provide a larger bandwidth, thus allowing parameters related to the vowel quality to be estimated. Particular attention will be paid towards traceability assurance and uncertainty estimation and a calibration procedure for each of the estimated parameters will be proposed. In this work, a DAQ-Board based set-up has been used instead of a portable micro-controller 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 (SPL) and fundamental frequency (F0).