Effect of vegetation on sound fields in idealised urban open spaces

Noise pollution is a major environmental problem within the EU and during the last years vegetation was examined for its benefits in increasing health and well-being of citizens from different viewpoints, including noise control and soundscape enhancement. This work focuses on numerical simulations to investigate the effectiveness of vegetation for controlling sound fields, especially in terms of the abatement of traffic noise. Two idealised urban squares were studied, one rectangular and one octagonal. Three plant types, climbing plants (ivy), living green walls with soil substrate and plants in pots (nephrolepis exaltata), were used in this investigation, based on their measured properties in laboratory, and four aspects of the use of vegetation were evaluated: effect of the amount of vegetation, effect of changing in the scattering coefficient of vegetation, effect of vegetation in different receiver positions and effect of vegetation on different groups of receivers. Parametric studies on the determination of a line source and on the definition of sound power levels referred to traffic noise were also developed. Three simulation tools were used, namely CATT-Acoustic®, CRR (Combined Ray-tracing and Radiosity) and Odeon

THE EFFECT OF CLASSROOM ACOUSTICS ON STUDENTS’ LEARNING PROCESSES: SELECTION OF OBJECTIVE PARAMETERS AND PROVISION OF A MEASUREMENT PROTOCOL

Since the students’ learning process is affected by classroom acoustics, this work is based on a literature review aiming at identifying the acoustical parameters that have major influence on students’ academic performances. The review strategy involved three different approaches and resulted in more than 30 selected papers, of which only a few provided information on the effects of the acoustics of the environment on learning. The indexes that turned out to have the greater influence on students' performance were therefore considered on the evaluation of acoustical quality in elementary school classrooms through in-field measurements. Room acoustics and intelligibility indices in both occupied and unoccupied conditions of twenty-nine first-grade classrooms belonging to 13 school buildings in Turin that differ in location and typology, were gathered in the study. Then, the association between objective parameters was assessed with linear regression analysis and results of previous studies were confirmed. In addition to that, new important considerations useful for the creation of a simplified protocol that can be universally applied when performing acoustic measurements in classrooms emerged, so that comparisons across several environments can be performed

Duration of voicing and silence periods of continuous speech in different acoustic environments

This work deals with the duration of voicing and silence periods of continuous speech in rooms with very different reverberation times (RTs). Measurements were conducted using the Ambulatory Phonation Monitoring (APM) 3200 (Kaypentax) and Voice-Care devices (developed at the Politecnico di Torino, Italy), both of which have a contact microphone placed on the base of the neck to detect skin vibrations during phonation. Six university professors and 22 university students made short laboratory monologs in which they explained something that they knew well to a listener 6m away. Seven students also described a map with the intention of correctly explaining directions to a listener who drew the path on a blank chart. Longer speech samples were made by primary school teachers in classrooms. A tendency to increase the voicing periods as the RT increased was on average observed for the university professors, the school teachers, and the university students who described a map. These students also showed longer silence periods than the students who made short monologues. The recognized trends concerned voice professionals or subjects who were highly motivated to make themselves understood in a perturbed speaking situation. Nonparametric statistical tests, which were applied to detect the differences in distributions of voicing and silence periods, have basically supported the findings

La comprensione del parlato in aule scolastiche con scenari acustici complessi

È nota l’influenza negativa del rumore e della riverberazione sull’intelligibilità del parlato. In questo lavoro sono state conside-rate due aule scolastiche con tempo di riverberazione di 0,4 s e 3,1 s. Sottoponendo un test d’ascolto ad un campione di 43 adulti normoudenti, è stata valutata l’influenza (i) del rumore energetico ed informativo, (ii) della riverberazione, (iii) della posizione della sorgente di rumore rispetto all’ascoltatore e (iv) della distanza tra parlatore e ascoltatore, sull’intelligibilità del parlato in termini di speech recognition threshold (SRT) e spatial release from masking (SRM)

Remote Working in the COVID-19 Pandemic: Results From a Questionnaire on the Perceived Noise Annoyance

Noisiness in the working environment was largely proved to have effects on the working activity and performance. To limit the spreading of the COVID-19 pandemic in the first wave between March and May 2020, Italian workers had massively started performing remote working. Insights on the subjective perception of noise annoyance under the remote working settings were thus necessary. Workers from a university and from several large and small Italian companies, resulting in 1,934 participants overall, answered to a questionnaire on the perception of noise annoyance in the remote working environment. A total of 57% of the responding workers stated to be sensitive to noise. The questionnaire was delivered online; data were recorded anonymously and then aggregated for statistical analyses. Results show that 55% of the workers perform their activity in an isolated room of the home environment, 43% in a shared room (e.g., kitchen, living room), and 2% in an outdoor space, with the majority of workers (57%) performing activity without other people in the environment. Among the noise sources investigated, 25% of workers recognize the noise generated by people (e.g., talking, moving, calling, listening to music) as the main source of disturbance. The negative consequences of noise annoyance during the remote working hours are mainly related to a loss of concentration and to a difficulty in relaxing. Furthermore, workers reported to get easily irritated by noise generated from the neighborhoods or from the housemates as it tends to distract from finishing a task

Speech sound pressure level distributions and their descriptive statistics in successive readings for reliable voice monitoring

Due to the high prevalence of voice disorders among teachers, there is a growing interest in monitoring voice during lessons. However, the reliability of the results is still to be deepened, especially in the case of repeated monitorings. The present study thus investigates the speech Sound Pressure Levels (SPL) variability under repeatability conditions aiming to provide preliminary normative data for the results assessment. In a semi-anechoic chamber, 17 subjects read twice and subsequently two phonetically-balanced passages, which were simultaneously recorded with a sound level meter, a headworn microphone and a portable vocal analyzer. Each speech sample was characterized through the distribution of SPL occurrences and several descriptive statistics of SPL distribution were calculated. For each subject, statistical differences between the two SPL distributions related to each passage were investigated using the Mann-Whitney U-test. For each group of subjects using the same device, the Wilcoxon signed-rank test was applied to the paired lists of descriptive statistics related to each passage. For mean, mode and equivalent SPL, the within-speaker and the within-group variability were assessed for each device. For all the devices and SPL parameters, the within-speaker variability was not higher than 2 dB while the within-group variability reached 5.3 dB

Effect of masks on speech intelligibility in auralized classrooms

This study explored the effects of wearing face masks on classroom communication. The effects of three different types of face masks (fabric, surgical, and N95 masks) on speech intelligibility (SI) presented to college students in auralized classrooms were evaluated. To simulate realistic classroom conditions, speech stimuli were presented in the presence of speech-shaped noise with a signal-to-noise ratio of +3dB under two different reverberation times (0.4s and 3.1s). The use of fabric masks yielded a significantly greater reduction in SI compared to the other masks. Therefore, surgical masks or N95 masks are recommended in teaching environments

Acustica delle aule scolastiche: un esempio di intervento di miglioramento innovativo e integrato

Garantire le condizioni acustiche ottimali per la trasmissione di messaggi vocali nelle aule scolastiche di qualsiasi ordine e grado deve essere l’obiettivo primario della buona pratica progettuale. La cattiva acustica nelle aule scolastiche, in termini di eccessivi livelli di rumore e elevati tempi di riverberazione, ricade negativamente sui docenti e sui discenti

Professional voice use in high school classrooms: relationships between classroom acoustics and voice parameters of teachers at the beginning and at the end of a school year

Objective: To accurately determine changes in the voice use of teachers along a school year. Furthermore, the relationship between vocal parameters, classroom acoustics and noise is statistically investigated. Methods: 37 teachers from two high schools in Torino (Italy) participated in this study at the beginning of a school year. 32 of them took part in the study also at the end of the same school year. In each period teachers were monitored repeatedly, adopting the same procedure, using the Voice Care device, which consists in a contact microphone to be placed at the jugular notch connected to a data logger. Vocal acquisitions contained information on the voice-use for entire lessons, from which plenary lesson monitorings were extracted since they require the highest phonation load. Each teacher performed an interview before each monitoring to obtain a conversational speech level. Sound pressure level (SPL), fundamental frequency (F0) and phonation time percentage (Dt%) were evaluated to characterize the vocal behavior and fatigue under different lessons and periods. A perceptual assessment of voice was also performed to investigate changes in the vocal health of teachers along a school year. Results: Voice parameters were analyzed in relation with the reverberation and noise conditions in which they were measured. Overall, it appeared that teachers adjust their voice significantly with the reverberation time both at the beginning and at the end of the school year, as well as with noise. Moreover, teachers who worked in worst acoustic conditions showed an increase in SPL at the end of the school year. Conclusions: Classroom acoustics and noise significantly influence teachers’ voice throughout an entire school year. To prevent from voice-related pathologies it is therefore important to solve acoustical issues as well as to determine a prevention program that easily allows monitoring the voice status of professionals in their workspaces

A longitudinal study on vocal behavior of teachers in classrooms and relationships with classroom acoustics

The objective of the longitudinal study presented in this work is twofold: to determine changes in the voice use of teachers along a school year and to study the relationships between voice and classroom acoustics parameters, which account for the background noise level during the teaching hours too. Thirty-one teachers from two secondary schools in Torino (Italy) were involved at the beginning of a school year and twenty-two of them participated in the monitoring campaign also at the end of the same school year too. Teachers adjust their voice significantly with noise and reverberation, both at the beginning and at the end of a school year. Moreover, teachers who worked in worst classroom acoustic conditions showed higher voice sound pressure levels at the end of the school year. Finally, a good predictive model to estimate the sound pressure level in front of the speaker’s mouth from the background noise level and the reverberation time was found