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Excessive road traffic noise exposure in (sub)urban parks hinders its restorative function and will negatively impact the number of visitors. Especially in such green environments, noise abatements by natural means, well integrated in the landscape, are the most desired solutions. Although dense vegetation bordering the park or raised berms could come first in mind, local landscape depressions are typically underused. In this work, a case-study of a small suburban park, squeezed in between two major arterial roads, is analyzed. The spatially dependent road traffic noise exposure in the park is assessed in detail by mobile sound pressure level measurements. Local reductions of up to 6-7 dBA are found at landscape depressions of only a few meters deep. It can therefore be concluded that this is an efficient measure and should be added to the environmental noise control toolbox for noise polluted parks.

Background: It remains unclear whether revascularization of moyamoya vasculopathy (MMV) has a positive effect on cognitive function. In this prospective, single-center study, we investigated the effect of revascularization on cognitive function in patients with MMV. We report clinical and radiological outcome parameters and the associations between clinical determinants and change in neurocognitive functioning. Methods: We consecutively included all MMV patients at a Dutch tertiary referral hospital who underwent pre- and postoperative standardized neuropsychological evaluation, [15O]H2O-PET (including cerebrovascular reactivity (CVR)), MRI, cerebral angiography, and completed standardized questionnaires on clinical outcome and quality of life (QOL). To explore the association between patient characteristics, imaging findings, and change in the z-scores of the cognitive domains, we used multivariable linear- and Bayesian regression analysis. Results: We included 40 patients of whom 35 (27 females, 21 children) were treated surgically. One patient died after surgery, and two withdrew from the study. TIA- and headache frequency and modified Rankin scale (mRS) improved (resp. p = 0.001, 0.019, 0.039). Eleven patients (seven children) developed a new infarct during follow-up (31%), five of which were symptomatic. CVR-scores improved significantly (p < 0.0005). The language domain improved (p = 0.029); other domains remained stable. In adults, there was an improvement in QOL. We could not find an association between change in imaging and cognitive scores. Conclusion: In this cohort of Western MMV patients, TIA frequency, headache, CVR, and mRS improved significantly after revascularization. The language domain significantly improved, while others remained stable. We could not find an association between changes in CVR and cognitive scores.

In this intervention study, a mobile measurement procedure has been explored to get insight in the noise mitigation performance of a complex shaped berm near a highway. Focus was on reducing sound pressure levels on a cycling path. Mobile measurements, before and after the execution of the plans, using the same methodology, stress that both the exposure to environmental noise and the efficiency of mitigation measures can be strongly spatially dependent. Furthermore, practical constraints during the implementation of the noise abatement have a strong impact on the final efficiency. Maps based on mobile measurements show to be an interesting learning tool for spatial planners, pointing at the consequences of deviations from acoustically optimized plans. When the mobile measurements are able to provide a sufficient temporal and spectral detail, more advanced analyses are possible as well. In this work, as an example, the difference between the C-weighted and A-weighted total level allowed a more detailed understanding of the efficiency of the road traffic noise intervention.

Acoustic comfort is becoming an increasingly important dimension for practitioners in the context of design of care facilities for older adults, namely nursing homes. Defining the quality of these spaces based on room acoustics criteria alone might be challenging if aspects related to their functioning (e.g., speech-based activities) are not taken into account. The acoustical capacity concept has been previously proposed for eating establishments as a way to provide a quality assessment based on both physical characteristics of the space and the perceived quality of verbal communication. In this study, a revised version of a prediction model for ambient noise levels based on occupancy and an estimation of acoustical capacity are proposed for nursing homes hosting people with dementia, and the corresponding parameters of slope, group size and absorption per person are optimized for the specific application, using a Nursing Home in Flanders (Belgium) participating to the AcustiCare project as case study. Results show that, compared to normal eating establishments, lower absorption per person values and higher group size values should be used in nursing homes to reduce errors in ambient noise levels prediction. Furthermore, using a retrofit intervention carried out in the living room of the Nursing Home, the enhanced acoustical capacity of the space was analysed. Results, in this case, show that, prior to the retrofit intervention, the acoustical capacity was already exceeded with average occupancy (i.e., saturated in normal functioning conditions), while the reduction in reverberation time achieved with the retrofit increased considerably the acoustical capacity of the space, shifting the quality of verbal communication in the living room from insufficient to satisfactory.

Gabions - metal-wired cages filled up with stones - are increasingly becoming popular as decorative elements and land property boundaries. It has been shown before that such structures can be used as road traffic noise barriers as well. However, the types of stones used in gabions have not been experimentally studied so far. Exploratory measurements at full scale in a semi-anechoic room were performed to study the effect of both porous and rigid stones on their noise reducing potential. At the 1/3 octave bands below 1 kHz, low-height gabions (with depths of 20 cm and 30 cm) hardly provide any sound pressure level reduction. At higher sound frequencies, in contrast, the shielding rapidly increases. Porous lava stones were found to significantly increase the shielding compared to rigid stones. Reflections on such nondeep low-height barriers towards the source side were found to be of minor importance when considering a standardized A-weighted road traffic noise spectrum. (C) 2018 Elsevier Ltd. All rights reserved.

As noise is a basic contributor to the evaluation of an environment, the indoor environment of a nursing home (where residents are provided with 24- hour functional support and care) is studied with this focus. General research results, as indicated from a literature review, are limited up till now. Using quantitative and qualitative methods five nursing homes in Flanders were studied before and after acoustic interventions. Sound levels were measured in individual bedrooms, living rooms and corridors to obtain the typical levels during a day. Acoustic intra-room performance parameters (reverberation time) and inter-room performance parameters (airborne noise insulation level and impact noise insulation level) were measured and compared with Belgian target values. The post operam measurements indicated the potential of the acoustic interventions (use of acoustic curtains, wall and ceiling panels, ventilations grills, floating floors) to improve the building performance and the acoustic climate. From a qualitative viewpoint, the thematic analysis of staff response to the acoustic interventions indicated direct positive outcomes (e.g., more pleasant, quieter indoor soundscapes) with both positive and negative outcomes from perceived indirect effects (i.e., non-acoustic factors).

In recent years, there has been an increasing interest in replacing digital subtraction angiography (DSA) as method of choice for the diagnostic imaging of patients suffering from lower extremity peripheral arterial disease (PAD). Due to small vessel diameters and suboptimal resolution, examinations of below-the-knee arteries however remain extremely challenging. The advent of wide beam CT scanners allows to perform multiple CT acquisitions over a wide patient volume. A sequence of these CT acquisitions at timed intervals could provide additional hemodynamic information, and as such allows to track a contrast bolus that propagates through the arterial conduit. The aim of this study was to evaluate the accuracy and precision of flow velocity measurements using time-resolved computed tomography angiography (CTA). To this end, we constructed a mechanical flow phantom (single lumen, 6 mm inner-diameter). Six consecutive time-resolved CTA acquisitions were performed at a constant flow rate to achieve six referencevelocities (21.2 mm/s, 38.9 mm/s, 60.1 mm/s, 81.4 mm/s, 99.0 mm/s and 120.3 mm/s). The mean centerline flow velocity was obtained from the contrast propagation over three different segmental lengths (160 mm, 80 mm and 40 mm) and then compared to the reference flow velocity. The results of this study suggest that mean flow velocities within the range of typical blood flow velocities in the below-the-knee arteries (40 mm/s - 70 mm/s), can be accurately measured with high precision in a 6 mm flow phantom using time-resolved CTA when considering a minimal path length of 80 mm.

The application area of distortion product otoacoustic emissions (DPOAEs) is expanding beyond clinical routines, towards new measurement environments, protocols, wearable hardware and more robust algorithms. To enable systematic assessment of the performance of commercial and prototype OAE equipment under various measurement conditions without a need for recruitment of the test subjects, a DPOAE generator that produces a reliable and stable response is proposed. This article suggests simple design for such generator that is easy to reproduce by third parties. This design uses an approximate model for middle and inner ear dynamics focusing on typical operational conditions. The DPOAE generator is embedded in a head and torso simulator enabling testing for various probe fitting and also residual ear canal volume effects. Measurement of the DPOAE generator response with clinical equipment shows that the response obtained falls within the range of human normative data. It is also shown that the generator is applicable outside the clinical routines and is able to highlight differences in measurements obtained with different clinical OAE measurement devices.

Recently there has been an increasing interest in the acoustic environment and its perceptual counterpart (i.e., the soundscape) of care facilities and their potential to affect the experience of residents with dementia. There is evidence that too loud sounds or poor soundscape quality more generally can affect negatively the quality of life of people with dementia and increase agitation. The AcustiCare project aims to use the soundscape approach to enhance the Quality of Life (QoL) of residents and to reduce Behavioral and Psychological Symptoms of Dementia (BPSD), as well as improving the everyday experience of nursing homes for both residents and staff members. In order to gain further insights into the sound environments of such facilities, sound level monitoring and soundscape data collection campaigns were conducted in the living rooms of five nursing homes in Flanders. Results showed that sound levels (dB) and loudness levels (sone) did not vary significantly between days of the week, but they did so between moments of the day and between living rooms. From the perceptual point of view, several soundscape attributes and the perceived prominence of different sound source types varied significantly between the living rooms investigated, and a positive correlation was found between sound levels and the number of persons present in the living rooms. These findings claim for further attention on the potential role of the sound domain in nursing homes, which should promote (and not only permit) better living and working conditions for residents and staff members of nursing homes.

Sound and its resulting soundscape is a major appraisal component of the living environment. Where environmental sounds (e.g., outdoor traffic sounds) are often perceived as negative, a soundscape (e.g., containing natural sounds) can also have a positive effect on health and well-being. This supportive effect of a soundscape is getting increasing attention for use in practice. This paper addresses the design of a supportive sonic environment for persons with dementia in nursing homes. Starting from a review of key mechanisms related to sonic perception, cognitive deficits and related behavior, a framework is derived for the composition of a sonic environment for persons with dementia. The proposed framework is centered around using acoustic stimuli for influencing mood, stimulating the feeling of safety and triggering a response in a person. These stimuli are intended to be deployed as added sounds in a nursing home to improve the well-being and behavior of the residents. ispartof: INTERNATIONAL JOURNAL OF ENVIRONMENTAL RESEARCH AND PUBLIC HEALTH vol:16 issue:24 ispartof: location:Switzerland status: published

Purpose: Run-off Computed Tomography Angiography (run-off CTA) of the lower extremities has become the method of choice for the diagnostic imaging of patients suffering from peripheral arterial disease (PAD). However, it remains a challenging radiological examination with a considerable risk of non-diagnostic image quality for the assessment of below-the-knee arteries. In this study, we investigate the diagnostic benefit of adding time-resolved CT scan series to the standard run-off CTA by performing repeated axial acquisitions over the calves of the patient during a second bolus of iodinated contrast injection. Materials and Methods: This prospective study included 20 patients (9 male, 11 female; mean age 66.1 ± 14.9 years) who received a standard run-off CTA and an additional time-resolved CT scan series after a 10 min delay. The time-resolved series consisted of 18 repeated axial acquisitions over the calves directly below the knee with a 2 s interphase delay. For both series, two observers independently assessed the anterior tibial, posterior tibial and peroneal arteries of both legs for following criteria: arterial enhancement, presence and degree of stenosis, the confidence of grading, degree of stenosis and venous overlay. Quantitative assessment of arterial enhancement was performed by measuring the mean CT values (HU) in all arteries. Radiation exposure was quantified by the effective dose. Results: A total of 118 arteries were assessed. The observer study showed that the additional time-resolved series improved both arterial enhancement (64% considered optimal enhanced versus 44%) and diagnostic confidence (59% considered as certain versus 33%) for the assessment of arterial stenosis (all p < 0.05). Venous overlay reduced from 15% to 6%. In all three arteries, the measured contrast enhancement by CT values (HU) was considerably higher (average 48%, p < 0.05) with the time-resolved series. The time-resolved series had an effect on stenosis classification (p = 0.03): a higher number of arteries were graded as having a non-significant stenosis (78.8% versus 71.2%). The interobserver variability in stenosis classification improved from κ = 0.39 to κ = 0.61. The mean effective dose was 5.1 ± 1.3 mSv for the run-off CTA and 0.2 ± 0.07 mSv for the time-resolved series. Per patient, a total volume of 140 mL contrast agent was injected. Conclusion: A dynamic CT scan protocol with repeated axial series can be added to a standard helical run-off CTA sequence for the lower extremities within the same CT examination, and it increases image quality and diagnostic confidence for the assessment of presence and degree of arterial stenosis in below-the-knee arteries.

The prevalence of Cryptosporidium and Giardia was studied on 10 intensively reared sheep and goat farms in the province of East Flanders, Belgium. Random faecal samples were collected and examined using the Merifluor((R)) immunofluorescence assay. Cryptosporidium positive samples were withheld for molecular identification using primers targeting the 18S rDNA, 70 kDa heat shock protein and 60 kDa glycoprotein gene. For the molecular identification of Giardia the beta-giardin gene and a recently developed assemblage specific PCR based on the triose phosphate isomerase gene were used. The prevalence of Cryptosporidium in lambs was 13.1% (18/137), on 4 out of 10 farms. In goat kids the Cryptosporidium prevalence was 9.5% (14/148), on 6 out of 10 farms. The molecular characterisation of Cryptosporidium positive isolates indicated that in lambs (n=10) the cervine genotype was predominant, whereas in the goat kids (n=11) only C. parvum was identified, with subgenotypes IIaA15G2R1 and IIdA22G1. The Giardia prevalence was 25.5% (35/137) in lambs with all 10 farms being positive, and 35.8% (53/148) in goat kids with 8 out of the 10 farms being positive. Both in the goat kids and in the lambs the host specific assemblage E was most commonly identified. However, the zoonotic assemblage A was identified in 6 out of 28 goat kids and in 2 out of 8 lambs, based on the beta-giardin sequence alignment. Using the assemblage specific PCR, mixed assemblage A and E infections were additionally identified in 2 lambs and in 5 goat kids. The results of the present study indicate that both Cryptosporidium and Giardia are common parasites on intensively reared sheep and goat farms in the province of East Flanders, Belgium, and that they are a potential source for zoonotic infections.

The effect of noise mitigation measures is generally expressed by noise levels only, neglecting the listener׳s perception. In this study, an auralization methodology is proposed that enables an auditive preview of noise abatement measures for road traffic noise, based on the direction dependent attenuation of a priori recordings made with a dedicated 32-channel spherical microphone array. This measurement-based auralization has the advantage that all non-road traffic sounds that create the listening context are present. The potential of this auralization methodology is evaluated through the assessment of the effect of an L-shaped mound. The angular insertion loss of the mound is estimated by using the ISO 9613-2 propagation model, the Pierce barrier diffraction model and the Harmonoise point-to-point model. The realism of the auralization technique is evaluated by listening tests, indicating that listeners had great difficulty in differentiating between a posteriori recordings and auralized samples, which shows the validity of the followed approaches.

Abating road traffic noise pollution is one of the main urban environmental challenges nowadays. However, architects and urbanists take decisions on urban regulations that define the shape of streets and buildings without taking this aspect into account. Furthermore, there is little information about the influence of urban geometry on traffic noise exposure in streets. In this study, the effect of street canyon design on sound pressure level distribution is numerically studied in high detail with the full-wave finite-difference time-domain method (FDTD). The CNOSSOS equivalent source power spectra were used to approach road traffic noise sources along two traffic lanes. Receivers both along the facades and the sidewalks have been considered in 42 cases. Numerical results demonstrate that building shape, street geometry and the presence of street furniture can have a strong impact on people's noise exposure. Building shape can be responsible for variations of up to 7.0 dB(A) at pedestrians. Building-facade design can reduce the average exposure at windows with 12.9 dB(A). It was further predicted that street geometry can enhance the positive effect of low barriers to 11.3 dB(A) along sidewalks. It was therefore concluded that carefully designing building facades and street geometry could improve the sound climate for people living and walking along busy urban streets and should be considered in future urban street design.

Microphone arrays are becoming increasingly popular for conferencing applications and near-field speech recording. In this work, a 16-element cylindrical microphone array is designed for beamforming towards a nearby speaker, while reducing the influence of competing talkers. A two-stage approach is used to obtain the desired array directivity pattern, optimizing both microphone locations and filter weights. The positions of the microphones are optimized by using a hybrid optimization technique, taking into account the influence of the nearby acoustic environment. FIR filter coefficients for each microphone are derived from a regularized least-squares (LSQR) solution, combined with null-steering. The performance of the design is evaluated experimentally and compared with a classically used goose-neck microphone.

Street reverberation can strongly increase sound pressure levels in urban streets. In noise mapping models on the other hand, including a sufficient number of reflections is computationally very costly. A simple regression model is developed in this study, based on typical street width and facade height or facade roughness in old city centers of many European cities. This model is based on measurements with a mobile setup in 99 streets in the city of Ghent, Belgium, representative for common European city morphology. The reflection ratio (RR) is used as a parameter to determine the energy contained in the reverberation part of the sound field. The model has been successfully validated by detailed measurements at different source-receiver distances in an urban street canyon.

Requirements for static (prediction of L(den) and diurnal averaged noise pattern) and dynamic (prediction of 15 min and 60 min evolution of L(Aeq) and statistical levels L(A90,)L(A50) and L(A10)) noise level monitoring are investigated in this paper. Noise levels are measured for 72 consecutive days at 5 neighboring streets in an inner-city noise measurement network in Gent, Flanders, Belgium. We present a method to make predictions based on a fixed monitoring station, combined with short-term sampling at temporary stations. It is shown that relying on a fixed station improves the estimation of L(den) at other locations, and allows for the reduction of the number of samples needed and their duration; L(den) is estimated with an error that does not exceed 1.5 dB(A) to 3.4 dB(A) according to the location, for 90% of the 3 × 15 min samples. Also the diurnal averaged noise pattern can be estimated with a good accuracy in this way. It was shown that there is an optimal location for the fixed station which can be found by short-term measurements only. Short-term level predictions were shown to be more difficult; 7 day samples were needed to build models able to estimate the evolution of L(Aeq,60min) with a RMSE ranging between 1.4 dB(A) and 3.7 dB(A). These higher values can be explained by the very pronounced short-term variations appearing in typical streets, which are not correlated between locations. On the other hand, moderately accurate predictions can be achieved, even based on short-term sampling (a 3 × 15 minute sampling duration seems to be sufficient for many of the accuracy goals set related to static and dynamic monitoring). Finally, the method proposed also allows for the prediction of the evolution of statistical indicators.

Thesis (MA)--PU vir CHO "No abstract available" Masters

The massive production of microphones for consumer electronics, and the shift from dedicated processing hardware to PC-based systems, opens the way to build affordable, extensive noise measurement networks. Applications include e.g. noise limit and urban soundscape monitoring, and validation of calculated noise maps. Microphones are the critical components of such a network. Therefore, in a first step, some basic characteristics of 8 microphones, distributed over a wide range of price classes, were measured in a standardized way in an anechoic chamber. In a next step, a thorough evaluation was made of the ability of these microphones to be used for environmental noise monitoring. This was done during a continuous, half-year lasting outdoor experiment, characterized by a wide variety of meteorological conditions. While some microphones failed during the course of this test, it was shown that it is possible to identify cheap microphones that highly correlate to the reference microphone during the full test period. When the deviations are expressed in total A-weighted (road traffic) noise levels, values of less than 1 dBA are obtained, in excess to the deviation amongst reference microphones themselves.