Measurement of noise events in road traffic streams: initial results from a simulation study

A key question for road traffic noise management is whether prediction of human response to noise, including sleep quality, could be improved over the use of conventional energy equivalent, or percentile, measures, by accounting for noise events in road traffic streams. This paper reports initial results from a noise-events investigation into event-based indicators over an exhaustive set of traffic flow, traffic composition, and propagation distance, conditions in unshielded locations in proximity to roadways. We simulate the time-varying noise level histories at various distances from roadways using a dynamic micro-traffic model and a distribution of sound power levels of individual vehicles. We then develop a comprehensive set of noise event indicators, extrapolated from those suggested in the literature, and use them to count noise events in these simulated time histories. We report the noise-event algorithms that produce realistic, and reliable, counts of noise events for one-hour measurement periods, then reduce redundancy in the indicator set by suggesting a small number of representative event indicators. Later work will report the traffic composition and distance conditions under which noise event measures provide information uncorrelated with conventional road traffic noise indicators — and which thus may prove useful as supplementary indicators to energy-equivalent measures for road traffic noise

Acoustical barriers in classrooms: the impact of noise on performance in the classroom

There is general concern about the levels of noise that children are exposed to in classroom situations. We report the results of a study that explores the effects of typical classroom noise on the performance of primary school children on a series of literacy and speed tasks. One hundred and fifty eight children in six Year 3 classes participated in the study. Classes were randomly assigned to one of three noise conditions. Two noise conditions were chosen to reflect levels of exposure experienced in urban classrooms (Shield & Dockrell, 2004): noise by children alone, that is classroom–babble, and babble plus environmental noise, babble and environmental. Performance in these conditions was compared with performance under typical quiet classroom conditions or base. All analyses controlled for ability. A differential negative effect of noise source on type of task was observed. Children in the babble and environmental noise performed significantly worse than those in the base and babble conditions on speed of processing tasks. In contrast, performance on the verbal tasks was significantly worse only in the babble condition. Children with special educational needs were differentially negatively affected in the babble condition. The processes underlying these effects are considered and the implications of the results for children’s attainments and classroom noise levels are explored

Noise event measures for road traffic

How should noise events in road traffic noise be measured? This paper reports the performance of a set of algorithms that detect noise events in time histories of road traffic noise in the population of acoustic conditions found near roadways. The latter was obtained through simulation of 500 different road traffic noise time histories using a comprehensive range of traffic flow, traffic composition, and propagation distance, conditions in unshielded locations near roadways. The initial set of algorithms tested was developed by systematically expanding on threshold-based algorithms described in the literature, then excluding those that were unreliable. The finding was that the NA50 and NA55 (detecting when road traffic noise exceeded 50 dB and 55 dB respectively), and the NAL50E10 (detecting when the traffic levels exceeded L50 + 10 dB) can all be considered for practical application as event detection indicators. All apply to measurement of indoor events with the windows of the dwelling open. The primary criterion for selection as supplementary indicators (and others in the same clusters that could substitute for them) was their non-monotonic relationship with the LAeq, The traffic and distance conditions under which these event-based measures could potentially be useful supplementary indicators is identified.Griffith Sciences, Griffith School of EnvironmentFull Tex

External and internal noise surveys of London primary schools

Internal and external noise surveys have been carried out around schools in London, UK, to provide information on typical levels and sources to which children are exposed while at school. Noise levels were measured outside 142 schools, in areas away from flightpaths into major airports. 86% of the schools surveyed were exposed to noise from road traffic, the average external noise level outside a school being 57 dB LAeq. Detailed internal noise surveys have been carried out in 140 classrooms in 16 schools, together with classroom observations. It was found that noise levels inside classrooms depend upon the activities in which the children are engaged, with a difference of 20 dB LAeq between the 'quietest' and 'noisiest' activities. The average background noise level in classrooms exceeds the level recommended in current standards. The number of children in the classroom was found to affect noise levels. External noise influenced internal noise levels only when children were engaged in the quietest classroom activities. The effects of the age of the school buildings and types of window upon internal noise were examined but results were inconclusive

Sound pleasantness evaluation of pedestrian walks in urban sound environments

ICA 2016, 22nd International Congress on Acoustics, BUENOS AIRES, ARGENTINE, 05-/09/2016 - 09/09/2016The health benefits of a daily physical activity, and of walking in particular, are widely acknowledged. However, walking in urban environment inevitably leads to an increased exposure to noise, which forms a drawback of choosing this transportation mode. Being able to estimate the sound pleasantness associated with an urban walk trip has many potential applications, such as informing pedestrians about the sound along their intended walk, which may help them to optimize their route choice. In the past decade, various studies have focused on characterizing and estimating the sound pleasantness perceived at specific locations, on the basis of perceptive and physical measurements. However, to estimate the sound pleasantness along an urban walking trip, an additional step is required, which consists of assessing how a pedestrian evaluates the overall pleasantness of a sound environment that varies along the walking trip. In this work, the results of two laboratory experiments and one field experiment are discussed, which were designed to assess the overall evaluation of the sound environment along an urban walk. Physical and perceptive measurements at specified positions or continuously along a series of tested routes are available, in addition to a global evaluation of the route. A comparison between the results of the three experiments provides a rich source of information to understand how the sound pleasantness of a pedestrian walk is evaluated. The main conclusion is that for short walks (of about 1 minute), a recency effect is observed, which tends to disappear when the duration of the walk increases

Tinnitus, medial olivocochlear system and music exposure in adolescents

The most common cause of tinnitus is the exposure to noise; in the case of adolescents, music is the main sound source they are exposed to. Currently, one of the hypotheses about the genesis of tinnitus is related to the deterioration in the functioning of the medial olivocochlear system (MOCS). The aim of this study was to determine the presence or absence of tinnitus in adolescents with normal hearing and to relate it to: (a) the functioning of the MOCS, by the contralateral suppression of the transient evoked otoacoustic emissions (TEOAEs) and (b) the musical general exposure (MGE). A cross-sectional descriptive correlational study was conducted. The sample was composed by adolescents with ages between 14 and 15. Two questionnaires were administered, one in relation to the subjective report of tinnitus and the other in relation to recreational activities to know the MGE. The results showed that the amplitude of frequencies (1000, 1500, 2000, and 3000 Hz) and global amplitude of TEOAEs, with and without acoustic contralateral stimulation, were higher in the group without tinnitus, with a statistically significant difference (P < 0.05). The suppressive effect was higher in the group without tinnitus; however, there was no statistically significant difference. Contrastingly, a significant association (P < 0.05) between exposure to music and tinnitus was observed; 72.41% of the adolescents with high exposure to music had tinnitus.Discussion and Conclusion:The results of the present investigation provide a contribution to the hypothesis of "the participation of the MOCS." Furthermore, a high MGE can be considered a risk factor for the onset of tinnitus.Fil: Hinalaf, María de Los Angeles. Universidad Nacional de Córdoba. Facultad de Medicina; Argentina. Centro de Investigación y Transferencia en Acústica; Argentina. Consejo Nacional de Investigaciones Científicas y Técnicas; ArgentinaFil: Maggi, Ana Luz. Consejo Nacional de Investigaciones Científicas y Técnicas; Argentina. Centro de Investigación y Transferencia en Acústica; ArgentinaFil: Hug, Mercedes Ximena. Consejo Nacional de Investigaciones Científicas y Técnicas; Argentina. Universidad Nacional de Córdoba. Facultad de Psicología; Argentina. Centro de Investigación y Transferencia en Acústica; ArgentinaFil: Kogan, Pablo. Centro de Investigación y Transferencia en Acústica; ArgentinaFil: Perez Villalobo, Jorge Alejandro. Centro de Investigación y Transferencia en Acústica; ArgentinaFil: Biassoni, Ester Cristina. Consejo Nacional de Investigaciones Científicas y Técnicas; Argentina. Centro de Investigación y Transferencia en Acústica; Argentin