Estimation procedure of the descriptor LAeq,T from the stabilization time of the sound pressure level value

Temporal structure of sound pressure level is a key aspect at the time of characterizing urban sound environments. In urban agglomerations, environmental noise levels fluctuate over a large range as a result of the great complexity of these settings, with considerable temporal and spatial heterogeneity. Furthermore, the domain in urban environments of noise sources, such as road traffic, commercial or leisure activities, construction works, etc., together with the occurrence of sudden sound-level maxima events (bells, sirens, vehicles at high traffic speed, honking horns...), which are quite frequent in urban agglomerations, generate the appearance of very high values of the impulsiveness of sound pressure level. This aspect causes a great influence on the time necessary for environmental noise levels to become stabilized, which is a key aspect for the accurate measurement, interpretation and guarantee of a statistically representative sample of a given urban sound environment. Therefore, the goal pursued in this work is to put forth a procedure for the calculation of a value of LAeq,T, representative of a certain urban location in a short-term time period, from the utilization of the value of the stabilization time of the sound pressure level

The Acoustics of the Palace of Charles V as a Cultural Heritage Concert Hall

This paper analyses the acoustic behaviour of the Palace of Charles V from a room acoustics perspective but also ponders the uniqueness of the space and its ability to engage and enhance the audience experience. The Palace of Charles V is a relevant part of the historical heritage of Granada. It has an architectural but also an acoustic uniqueness that deserves research. A measurement campaign was made to calculate parameters such as T30, IACC, C80 or Gm, and to explain the behaviour of the Palace. The BQI is quite high, but the late part of the impulse response (t > 80 ms) has strong unwanted reflections causing low clarity (C80) and listener envelopment (LEV). Nevertheless, the Palace is a successful concert venue with good feedback from musicians and the audience

A tool for urban soundscape evaluation applying Support Vector Machines for developing a soundscape classification model

To ensure appropriate soundscape management in urban environments, the urban-planning authorities need a range of tools that enable such a task to be performed. An essential step during the management of urban areas from a sound standpoint should be the evaluation of the soundscape in such an area. In this sense, it has beenwidely acknowledged that a subjective and acoustical categorization of a soundscape is the first step to evaluate it, providing a basis for designing or adapting it to match people's expectations as well. In this sense, this work proposes a model for automatic classification of urban soundscapes. This model is intended for the automatic classification of urban soundscapes based on underlying acoustical and perceptual criteria. Thus, this classificationmodel is proposed to be used as a tool for a comprehensive urban soundscape evaluation. Because of the great complexity associated with the problem, two machine learning techniques, Support Vector Machines (SVM) and Support Vector Machines trained with Sequential Minimal Optimization (SMO), are implemented in developing model classification. The results indicate that the SMO model outperforms the SVM model in the specific task of soundscape classification. With the implementation of the SMO algorithm, the classification model achieves an outstanding performance (91.3% of instances correctly classified)

Use of back-propagation neural networks to predict both level and temporal-spectral composition of sound pressure in urban sound environments

One of the main challenges of urban planning is to create soundscapes capable of providing inhabitants with a high quality of life. Urban planners need tools that enable them to approach the final goal of designing, planning, and assessing soundscapes in order to adapt them to the needs of the population. Nowadays, authorities have models for predicting the A-weighted equivalent sound-pressure level (LAeq). Nevertheless, it is necessary to analyze not only the (LAeq) parameter but also the temporal and spectral composition of the sound pressure in the soundscape considered. The problem of modelling and predicting environmental noise in urban settings is a complex and non-linear problem. Therefore, in the present study, a prediction model based on a back-propagation neural network to solve this problem is proposed and examined. This model (STACO model) is intended to predict the short-term (5-min integration period) level and temporal-spectral composition of the sound pressure of urban sonic environments. Here, it is shown that the proposed model yields a precise and accurate prediction. Moreover, the results in this work demonstrate the validity of generalization of the STACO model, being applicable not only for the situations/locations measured, but also for any situation/location of a medium-sized urban setting, with some prior adjustment. In summary, the prediction model proposed in this study may serve as a tool for the integration of acoustical variables in city planning

Required stabilization time, short-term variability and impulsiveness of the sound pressure level to characterize the temporal composition of urban soundscapes

Temporal composition of urban soundscapes is a very important aspect at the time of studying their description and perception. In urban agglomerations, environmental noise levels can vary over a wide range as a result of the great complexity of these settings, with considerable temporal and spatial heterogeneity. In addition, the presence of noisy sources, e.g. road traffic, commercial/leisure activities, construction works, etc., together with the appearance of sudden sound-level maxima (horn, sirens, vehicles with high traffic speed, etc.), very common in urban agglomerations, make the impulsiveness of the sound level very high in this type of environment. This will influence the time required for the noise levels to become steady, a key aspect for accurate measurement, interpretation and guarantee of a statistically representative sample of the urban soundscape. The goal of our research is to analyze the usefulness of the stabilization time, short-term temporal variability and impulsiveness of the sound pressure level in characterizing the temporal composition of urban soundscapes

Stability and efficiency of biofilms for landfill leachate treatment

The objective of this work was to assess the feasibility of a fixed-film biological aerated filtration process for the treatment of the leachate produced at Harnhill landfill site (South Gloucestershire, UK). The laboratory scale plant consisted of four identical biological aerated filters (a triplicate and a "control" column) packed with small brick fragments. Biofilm formed within 24 h of immersion of the support material in the reactor, and had a high resistance to antibiotics and other toxic agents. The plant maintained a stable operation in the 20-45 °C temperature range, showing the best results (35.4 ± 6.6% COD removal and 73.9 ± 5.5% BOD5 reduction) at 40 °C. The lowest COD and BOD5 values obtained at the outlet of the columns were 7067 mg/L and 1050 mg/L, respectively. © 2009 Elsevier Ltd. All rights reserved

Priority index on road sections for noise action plan (Índice para determinación de la prioridad de actuación en los tramos de carretera de un plan de acción contra el ruido)

It is well known that the road traffic noise is one of the most important contributors to the environmental impact generated by roads. There no exists hitherto any regulated guidance or procedure that establishes how to undertake a well-founded prioritization among the diverse road sections which are included in the corresponding Action Plans against noise according to the Environmental Noise Directive (2002/49/EC). In this work, the so-called “priority road stretch index” (PRSI) is developed. This index is based on a number of variables (called “priority road stretch variables”, PRSV), which are weighted according to their influence on the road traffic noise problem. This developed index allows sorting out by priority action the road sections included in the Noise Action Plans. Also, in order to test the validity of the proposed methodology, the “priority road stretch index” is applied to the Action Plan against Noise 2008-2012 of the road network of the regional government of Andalusia in the province of Almería