Several studies have shown so far that poor acoustics inside classrooms negatively affects the teaching and learning processes, especially at the lowest grades of education. However, the extent to which noise exposure or excessive reverberation affect well-being of children at school in their early childhood is still unanswered, as well as their awareness of noise disturbance. This work is a pilot study to investigate to which extent classroom acoustics affects the perceived well-being and noise disturbance in first graders. About 330 pupils aged from 6 to 7 years participated in the study. They belonged to 20 classes of 10 primary schools located in Torino (Italy), where room acoustic measurements were performed and where noise level was monitored during classes. The school buildings and the classrooms were balanced between socioeconomic status and acoustic conditions. Trained experimenters administered questionnaires in each class, where pupils answered all together during the last month of the school year (May). Questions included the happiness scale, subscales assessing self-esteem, emotional health, relationship at home and with friends, enjoyment of school, intensity and noise disturbance due to different sound sources, and quality of voice. The findings of the study suggest that long reverberation times, which are associated with poor classroom acoustics as they generate higher noise levels and degraded speech intelligibility, bring pupils to a reduced perception of having fun and being happy with themselves. Furthermore, bad classroom acoustics is also related to an increased perception of noise intensity and disturbance, particularly in the case of traffic noise and noise from adjacent school environments. Finally, happy pupils reported a higher perception of noise disturbance under bad classroom acoustic conditions, whereas unhappy pupils only reported complaints in bad classroom acoustics with respect to the perception of pleasances with himself or herself and of fitting in at school. Being a mother tongue speaker is a characteristic of children that brings more chances of attending classes in good acoustics, of being less disturbed, and of having more well-being, and richer districts presented better acoustic conditions, in turn resulting in richer districts also revealing a greater perception of well-being.

The need of tuning into speech in noisy and reverberant classrooms is a challenge for good speech communication and literacy development at school. Reading development can be compromised if children are exposed to inadequate acoustics, especially those with poor neural processing in speech discrimination. This work reports preliminary results on the influence of classroom acoustics on the reading speed of 94 Italian second-graders. Speech clarity (C50) was found to be significantly correlated with all the investigated reading tasks, while no significant correlations were found with reverberation time.

Traceability of digital sensors is a metrological challenge, as well as a present priority, as stated within the emerging metrology requirements for the future in the Strategy 2017 to 2027 document of the Consultative Committee for Acoustics, Ultrasound, and Vibration of BIPM. From this perspective, in this paper, a calibration system for 3-axis digital MEMS accelerometers is described, in order to simultaneously evaluate the main and transverse sensitivities in the frequency domain (from 5 Hz up to 3 kHz) and in static conditions, together with a proper sensitivity parameter for digital outputs, thus providing the required metrological traceability. The procedure, based on the comparison to a reference transducer, involves a single-axis excitation of inclined planes. Experimental results are expressed in terms of exploitation and sensitivities matrices. Overall expanded uncertainties of the main terms are in the order of 2%, in dynamic conditions, and 1%-2% in static conditions. The feasibility of this system can be exploited for the development of manufacturers' in-line control systems and for the investigation of large-scale calibration procedures.

Indoor working and living environments are increasingly exposed to low-frequency noise sources. The wellknown relationship between noise conditions and effects on human health requires the development of a proper procedure to evaluate the stress due to acoustical factors. For this purpose, an experiment, based on Soft Metrology principles, was designed to measure the changes of cognitive and physiological parameters (response time and heart rate) on a sample of 25 male and female volunteers, aged 19-29 years, exposed to three types of noise in a hemi-anechoic room. Participants were involved in a cognitive task (Stroop effect) for 10 min in four different conditions: silence, stochastic broadband multi-tonal noise (BBN), stochastic lowfrequency multi-tonal noise (LFN1), and low-frequency stationary noise with regular amplitude modulation (LFN2). All sounds were reproduced by two loudspeakers at equivalent sound pressure level of 93 dB. Results showed that in noise conditions, subjects reduced their response times. This is an evidence of growing stress, according to arousal theory. In particular, LFN1 and LFN2 produced cognitive stress comparable to stochastic broadband multi-tonal noise. Furthermore, subdividing the subjects in extroverts and introverts through the Eysenck Personality Questionnaire-Revised psychological test, it was shown that LFN1 and LFN2 produced higher stress effects than stochastic broadband multi-tonal noise on the cognitive performances and a physiological stress comparable to stochastic broadband multi-tonal noise in introverts, whereas no effects were observed in extroverts, as hypothesized by Eysenck. This result highlights the necessity in the future to consider the personality parameter as a key factor in the evaluation of the effects of noise on humans.

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Quantitative precipitation estimation and rainfall monitoring based on meteorological data, potentially provides continuous, high-resolution and large-coverage data, are of high practical use: Think of hydrogeological risk management, hydroelectric power, road and tourism. Both conventional long-range radars and rain-gauges suffer from measurement errors and difficulties in precipitation estimation. For efficient monitoring operation of localized rain events of limited extension and of small basins of interest, an unrealistic extremely dense rain gauge network should be needed. Alternatively C-band or S-band meteorological long range radars are able to monitor rain fields over wide areas, however with not enough space and time resolution, and with high purchase and maintenance costs. Short-range X-band radars for rain monitoring can be a valid compromise solution between the two more common rain measurement and observation instruments. Lots of scientific efforts have already focused on radar-gauge adjustment and quantitative precipitation estimation in order to improve the radar measurement techniques. After some considerations about long range radars and gauge network, this paper presents instead some examples of how X-band mini radars can be very useful for the observation of rainfall events and how they can integrate and supplement long range radars and rain gauge networks. Three case studies are presented: A very localized and intense event, a rainfall event with high temporal and spatial variability and the employ of X-band mini radar in a mountainous region with narrow valleys. The adaptability of such radar devoted to monitor rain is demonstrated.

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