This paper describes an ultrasonic sensor that is able to measure the distance from the ground of selected points of a motor vehicle. The sensor is based on the measurement of the time of flight of an ultrasonic pulse, which is reflected by the ground. A constrained optimization technique is employed to obtain reflected pulses that are easily detectable by means of a threshold comparator. Such a technique, which takes the frequency response of the ultrasonic transducers into account, allows a sub-wavelength detection to be obtained. Experimental tests, performed with a 40 kHz piezoelectric-transducer based sensor, showed a standard uncertainty of 1 mm at rest or at low speeds; the sensor still works at speeds of up to 30 m/s, although at higher uncertainty. The sensor is composed of only low cost components, thus being apt for first car equipment in many cases, and is able to self-adapt to different conditions in order to give the best results.

This paper deals with Cepstral Peak Prominence Smoothed (CPPS) distribution and its descriptive statistics as possible indicators of vocal health status. 41 voluntary patients and 35 control subjects participated in the experiment: all of them followed the same protocol, which includes three repetitions of the sustained vowel /a/ simultaneously acquired with a microphone in air and a contact sensor, the perceptual assessment of voice quality and the videolaringoscopy examination. The fifth percentile and the standard deviation of CPPS distribution were the parameters included in the best logistic regression models for the microphone in air and the contact sensor, respectively. The selected CPPS parameters had a strong to good discrimination power: an Area Under Curve of 0.95 and 0.87 has been found for the microphone in air and for the contact sensor, respectively. For each CPPS parameter, the repeatability has been also estimated and the Monte Carlo method has been implemented for the uncertainty evaluation of the discrimination threshold. Furthermore, preliminary recommendations for better accuracy and repeatability of future studies are provided: analyses on the main CPPS influence quantities and on the effect of the frequency content of the signal spectrum on the CPPS parameters have been provided. Index TermsCepstral analyses, human voice, biomedical measurement, acoustic devices, reproducibility of results, Monte Carlo methods, uncertainty I. INTRODUCTION Traditionally, voice quality has been assesed using subjective tests, in which experts listen to live or recorded vocal signals and perceptually rate them. In order to overcome the subjectivity and the expensiveness of such methods and with the aim to find a less time-consuming tool, researchers started to analyze voice signals and to extract several parameters as indexes of different aspects of voice and voice-related issues.

This paper deals with a wireless sensor network that was specifically designed to monitor temperature-sensitive products during their distribution with the aim of conforming to the cold-chain assurance requirements. The measurement problems and the constraints that have been encountered in this application are initially highlighted, and then, an architecture that takes such problems into account is proposed. The proposed architecture is based on specifically designed measuring nodes that are inserted into the products to identify their behavior under real operating conditions, e.g., during a typical distribution. Such product nodes communicate through a wireless channel with a base station, which collects and processes the data sent by all the nodes. A peculiarity of the product nodes is the low cost, which allows the information on the cold-chain integrity to be provided to the final customer. The results that refer to the functional tests of the proposed system and to the experimental tests performed on a refrigerated vehicle during a distribution are reported.

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The present study has investigated the occupational voice use of 27 female primary school teachers over a four-day-follow-up. Sixty-one working-day voice samples were acquired with two contact sensor-based vocal analyzers in four schools with highly different classroom acoustics. The vocal parameters were compared with a conversational task that the teachers performed before each lesson and with the measured classroom acoustic parameters. The average equivalent sound pressure level at 1 m from the mouth, which refers to the teacher's vocal effort, and the voicing time percentage were 71.2 dB [standard error (SE) 1.0 dB] and 29%, respectively. The teachers' mean voice level and fundamental frequency were significantly higher in the occupational setting than in the conversational one, which is by 5.5 dB (SE 0.5 dB) and 50 Hz (SE 3 Hz), respectively. Higher voice levels were observed for higher background noise levels, at a rate of 0.53 dB/dB, and a tendency of the background noise to increase with increasing reverberation time was observed at a rate of 13 dB/s. An optimal reverberation time of 0.7 s was found to minimize the voice level, since teachers raised their voice at lower and higher reverberation times, the latter presumably due to higher background noise levels.