bluuebunny/crossref_metadata_2025 huggingface dataset:
Gesture synthesis: basic control of a flute physical model
Authors: Montgermont Nicolas , Fabre Benoit , De La Cuadra Patricio
Published: May 2008

In the flute family, the oscillation is due to the instability of a jet at the output of a channel coupled with an acoustic resonator. Recent physical models allows to simulate the behavior of the complete instrument, but we still lack a convincing way to drive them. The simulation of the isolated instrument must be completed with a modelization of the control exerted by the flutist. Depending of the instrument of the flute family, the number and type of control parameters are differents. For example, in a recorder the player blows inside a fixed channel built by the instrument maker and in the case of the transverse flute, the channel is shaped by the player's lips during the playing. This paper presents a simple model of flute player, based on measurements carried on instrumentalists playing on a recorder or a transverse flute. The model is generating the basic features of the instrument control in order to produce given pitches and dynamics. The coupling with a flute physical model allows to study its validity.
Analysis of drum player's motion
Authors: Kawakami Hiroshi , Mito Yuki , Watanuma Reiji , Marumo Mieko
Published: May 2008

In this experiment, the motion of a drum player's arm was measured by the optical motion capture system in various performance types. From these actual movement data, we analyzed about the acceleration and sound energy flux of the stick before and after excitation. Moreover, the snap of a wrist which is very important at the time of a high drum performance and the relation of acceleration, and the relation of sound energy flux were also analyzed. From those results, it was suggested that the snap of the wrist was important at the time of a high drum performance, and it was concerned with sound power. Especially, the performance which player hit the drum speedy and repeatedly was concerned with the acceleration of stick before and after excitation.
Dampening vibration modes of the snare drum batter head
Authors: Larkin Barry , Morrison Andrew
Published: May 2008

Percussionists have always had to contend with an undesirable ringing sound while performing on the snare drum. It is usually referred to as the “edge ring.” A common method to eliminate this sound comes from placing some type of dampening material on the edge of the drum head. Manufacturers of drums have provided many ways of dealing with this problem including internal dampening devices, customized drums heads or material designed to be placed on the drum head. Using electronic television holography, it was revealed the source of this “ring” to be the third mode of vibration that produces a pitch approximately one octave and a half step above the fundamental [Larkin and Morrison, JASA, 122, #5, p 3056]. In this update to the previous work, we will show the effect of dampening devices on the third and other modes.
What/when causal expectation modelling applied to percussive audio
Authors: Hazan Amaury , Brossier Paul , Marxer Ricard , Purwins Hendrik
Published: May 2008

A causal system for representing a musical stream and generating further expected events is presented. Starting from an auditory front-end which extracts low-level (e.g., spectral shape, mel frequency cepstral coefficients) and midlevel features such as onsets and beats, an unsupervised categorisation process builds and maintains a set of symbols aimed at representing musical stream events using both timbre and time descriptions. The time events are represented using inter-onset intervals relative to the beats. These symbols are then processed by an expectation module based on predictive partial match, a multiscale technique derived from N-grams. The system capacity to generate an expectation that matches its transcription is evaluated using drum recordings from the ENST-drums database. We show that the MFCC-based representation leads to a more compact set of symbols and a better match between transcription and expectation. Also, we suggest that the system is sensitive to exposure and illustrate some properties of the expectation entropy while attending percussive audio patterns.
Dynamical hierarchical self-organization of harmonic and motivic musical categories
Authors: Marxer Ricard , Holonowicz Piotr , Hazan Amaury , Purwins Hendrik
Published: May 2008

We introduce a generic model of emergence of musical categories during the listening process. The model is based on a preprocessing and a categorization module. Preprocessing results in a perceptually plausible representation of music events extracted from symbolic input. The categorization module lets a taxonomy of musical entities emerge according to a cognitively plausible online learning paradigm. We show the advantages of using a conceptual clustering method in the musical domain. The system extracts multilevel hierarchies and can be tuned to clustering at various resolutions. The potential of the model is exemplified by exposing it to two different datasets resulting in music harmonic and motivic categorization consistent with music theory.
A comparison of molecular approaches for generating sparse and structured multiresolution representations of audio and music signals
Authors: Sturm Bob , Shynk John J. , McLeran Aaron , Roads Curtis , Daudet Laurent
Published: May 2008

The authors investigate the characteristics and performance of joint (single-step) and sequential (two-step) approaches to creating sparse and structured multiresolution representations of audio and music signals derived using sparse overcomplete methods. A joint approach, such as molecular matching pursuit, attempts to find structures in a signal as part of the decomposition process, while a sequential approach, such as agglomerative clustering, attempts to find structures in the completed decomposition of a signal. Each of these approaches have different benefits and drawbacks. For a joint approach, it is computationally convenient that the decomposition and structuring are done simultaneously, but usually only simple structural relations are possible. For a sequential approach, one is working in a parameter space of much smaller dimension than the original signal, but the computation is higher since the decomposition and the structure building are two separate processes. Results from these approaches using real audio and music signals will be compared and contrasted, and will contribute to our goal of creating an enhanced interface between the content of audio and music signals, e.g., onsets, notes, voices, and their multiresolution sparse atomic decompositions.
Early use of the Scott-Koenig phonautograph for documenting performance
Authors: Brock-Nannestad George , Fontaine Jean-Marc
Published: May 2008

Acoustics in the 1850s combined listening, observation and notation. This was “real-time”, catching any phenomenon as it appeared. If it was repeatable, one could prepare for it. Continuous data rather than observation data enabled a very different analysis from observation and notebooks. Édouard-Léon Scott's invention of the phonautograph enabled this. A surface moved below a stylus that was vibrated by sound in air. Originally a blackened glass plate, the scientific instrument maker Rudolph Koenig contributed by devising a very long axis representing time, because now blackened paper was wrapped around a cylinder on a threaded shaft. A two-dimensional representation of the individual vibrations was obtained. Scott both deposited a sealed letter with the Paris Academy of Sciences in January, 1857 and filed a patent application in April, 1857. Later he deposited a further sealed letter and in 1859 he filed an application for patent of addition. Following the thoughts expressed and documented in his manuscripts here analyzed in context and comparing with Koenig's production it is feasible to see how they were dependent on each other, although they had different purposes in mind. The paper concentrates on Scott's interests in performance, and a number of original tracings are discussed.
Bayesian inference in hierarchical non-negative matrix factorisation models of musical sounds
Authors: Cemgil Ali Taylan , Virtanen Tuomas
Published: May 2008

There has been a surge of interest to efficient audio and music modeling using tools from statistical machine learning. One such technique, that has been particularly successful, is non-negative matrix factorisation (NMF). However, a detailed theoretical understanding of this success is missing, as well as links to other modeling strategies such as sinusoidal or harmonic models. To fill this gap, we describe NMF in a statistical framework, as a hierarchical generative model consisting of an observation and a prior component. We show that particular choices lead to standard NMF algorithms as special cases, where parameter estimation is carried out via maximum likelihood. Starting from this view, we develop extensions that facilitate more realistic acoustic modeling (such as spectral smoothness or harmonicity of natural sounds) and alternative inference techniques via Gibbs sampling and variational Bayes, which allow us to do principled comparisons between alternative models via Bayesian model selection. Our novel construction, where we make use of Markov chains of Gamma random variables, retains conjugacy and enables us to develop models that fit better to real data while retaining attractive features of standard NMF such as fast convergence and easy implementation. We illustrate our approach on polyphonic pitch estimation.
Towards an adaptive subspace-based representation of musical spectral content
Authors: David Bertrand , Badeau Roland
Published: May 2008

This study presents an algorithm based on an adaptive framework model for musical sound signals assumed to be composed of slowly varying frequency components surrounded by additive noise. These components appear as contours in a time-frequency representation, as for instance, a spectrogram. To extract these contours, an often used solution is to estimate the parameters (amplitude, frequency, and phase) of each component at each frame and then to link them from one to the next with the help of a distance measure or an HMM. Conversely, our method attempts to update the estimated values from one time instant to the next. It relies on principal subspace tracking (with respect to time) together with gradient descent to individually update each of the component parameters. Finally, each extracted contour, which represents the frequency and amplitude variation of a single component, is available for subsequent processing. Applications are demonstrated in the fields of harmonic plus noise decomposition and analysis/transformation/synthesis. This research is supported by the french Institut Telecom, TAMTAM project.
Auditory model based analysis of polyphonic music
Authors: Klapuri Anssi
Published: May 2008

This study is about the use of an auditory model to extract multiple pitches from polyphonic music signals. One goal was to identify the conditions where pitch analysis using an auditory model is advantageous over more conventional time or frequency domain approaches. It is shown that these conditions include especially the processing of band-limited signals or signals where important parts of the audible spectrum are corrupted by band-limited interference. An efficient implementation strategy is described which reduces the computational complexity of the auditory model roughly by factor 10. Further prospects of bandwise processing and redundant signal representations in general are discussed.
On perceptual distortion measures and parametric modeling
Authors: Christensen Mads G.
Published: May 2008

Over the past two decades, there has been much interest in incorporating human sound perception in signal processing algorithms, often in the form of perceptual distortion measure or an approximation thereof. An example of this is MDCT-based audio coding where a good quality can be achieved at very low bit-rates by taking masking effects into account. More recently, the same principles have been applied to parametric modeling and coding of audio signals. We discuss the inherent tradeoffs in choosing a perceptual distortion measure and a parametric model and the pros and cons of various ways of implementing such perceptual distortion measures is discussed. An important question that we seek to answer is whether perception should be taken into account in the estimation of model parameters or this should be done in a separate step.
The jew's harp, experimental study and modeling
Authors: Besnainou Charles , Frelat Joel , Mamou-Mani Adrien
Published: May 2008

Under its archaic aspects jew's harp is a musical instrument highly subtle. Indeed, a metal blade (or wooden) attached to a rigid frame put into vibration by the musician, and coupled to the buccal resonator allow nice tune. The skilt of the jew's harp focuses on the conformations of this cavity whose function is to select the right components of the vibration to be amplify. In our study, we have modelled a playing technique which involves blowing during the blade vibrates. In the lake of breath, the spectre of sound produced by the blade is odd, i.e., it includes at first approximation odd components (n+1) multiple the fundamental. Whereas when the musician adds breath the spectrum turns into a spectrum containing all components of basic integer multiples (n). This work takes place in the context of studies of vibrating systems under prestress and loaded. In that case the load, and the prestress are generated by the musician breath by bending the blade On the other hand, experimental studies are compare with the model results.
Sound of the HANG
Authors: Rossing Thomas D. , Wessel David
Published: May 2008

Previous studies of the HANG [T. D. Rossing, U. Hansen, F. Rohner, and S. Schärer, 142nd ASA meeting, December 2001; T. D. Rossing, A. Morrison, U. Hansen, F. Rohner, and S. Schärer, Proceedings of ISMA07, Barcelona, 2007] have discussed the modes of vibration and the sound radiation field of the HANG when note areas are excited by sinusoidal force. Since the HANG is a hand-played steel instrument, a wide variety of playing techniques are used by various performers. We report on the sound of the HANG when played in various ways. Recordings of the HANG were made with a hemispheric microphone array. The instrument was excited by taking multiple samples of each of a number of striking techniques with the hand. These include single strokes from the soft part of the finger, as well as, the finger nail itself. Various grace note techniques like flams were also investigated. Damping was controlled by the time the finger remained in contact with the instrument, as well as, by using the palm. Force hammer measurements were also included. We report on these measurements and incorporate them in to an excited-resonance model of the instrument. Demonstrations of the real and modeled instrument will be provided.
How is hearing heard in second year architectural design education
Authors: Bauer Juergen
Published: May 2008

Architects are often accused of “not being interested in acoustics because it is invisible”. Surely, architectural design, particularly at preliminary stage, has always been driven visually: architects usually develop a project by vision, not by hearing. On the other hand, designing architects have to deal creatively with more or less invisible parameters: sociocultural demands, climatic aspects as wind or temperature, or even daylight which can be considered to be visible but certainly is everything but constant. If an architect's design ability is about observation and awareness, and to give an example, if light is considered to be much more than just being bright or dark, how then could we implement early awareness that sound is much more than noise or silence, and that sound planning is much more than just using anti-noise-panels? We asked second year architecture students at Waterford Institute of Technology to (re-)think the architecture of schools and to question the sound qualities and their own sound recollection of such an environment. The paper will outline the teaching approach and present some student's responses to the given aims and brief. Finally, the lessons learnt by teaching staff will be summarized.
Using the soundscape approach to develop a public space in Berlin - perception and evaluation
Authors: Schulte-Fortkamp Brigitte , Volz Rudi , Jakob Andre
Published: May 2008

In Berlin the Soundscape Project “Nauener Platz” is carried out to rebuild a difficult public space into a space which is dominated by social freedom. A designed space related procedure is developed following the soundscape approach, which will provide acoustical indicators and parameters describing urban and other outdoor living areas with respect to physical conditions and their relevance for life. The measurement of outdoor sound quality will take into consideration not only the sound pressure but also the characteristics of the sounds which lead to specific human reactions, both positive and negative: calmness, inspiration, annoyance, discontentment, anxiety, etc. and the pathogenic effects. Qualitative evaluations through soundwalks and open interviews have been conducted introducing the new experts. Framework and procedure will be discussed. The Soundscape Project is a module of the Project “Nauener Platz - Remodelling for Young and Old”in the framework of the research program “Experimental Housing and Urban Development (ExWoSt)” of the “Federal Ministry of Transport, Building, and Urban Affairs (BMVBS)” by the “Federal Office for Building and Regional Planning (BBR)”. It is related to the fields of research (ExWoSt) concerned with "Innovation of Urban Neighbourhoods for Families and the Elderly". The project executing organization is the Regional Office Berlin-Mitte.
Soundscape design methods to acheive net zero environmantal noise impacts
Authors: Siebein Gary W. , Lilkendey Robert M. , Paek Hyun
Published: May 2008

Soundscape design methods were developed to approach net zero environmental noise impacts for significant building projects in complex settings. Auralization methods for various design alternatives were presented for stake holder review in a large auditorium and in a full size demonstration in the actual environment. Innovative acoustical design and analysis methods were developed to economically reduce source noise levels to the vicinity of the ambient sound level. Methods to determine the nature of the ambient sound level as it varies with time of day, time of year, and other natural and community factors included a series of long term average A-weighted sound levels as well as more detailed octave band measurements and calibrated aural recordings of specific acoustic events. Sound walks were conducted at various times of day to understand the dynamics of the acoustical environment and to identify issues. Focus group discussions among stakeholders and team members developed the long term plans for the community and appropriate architectural and acoustical design criteria for the project.
The influence of subjective response on the choice of measurement for aircraft arrival noise at Nantucket Airport
Authors: Timmerman Nancy
Published: May 2008

The Nantucket Airport in Massachusetts serves primarily turboprop commuter aircraft, and private or charter jets, with most of its operations in the summer. A seasonal homeowner was severely affected by arrival flight noise and requested noise measurements and noise control recommendations for this architect-designed residence. Time was spent with the homeowner to understand steps already taken, and problems still causing trouble. Standard measurement procedures for aircraft operations in the United States call for the use of A-weighted, slow response for the assessment of noise impact. Since the noise sources at this airport have strong tonal components (from the propellers), and noise control recommendations were sought, one-second 1/3-octave band levels were used to both document the observed problem, and to estimate the field transmission loss of the windows and doors. Measurements were made during a Friday afternoon, when arriving aircraft were mostly 1.5 to 2 min apart. A-weighted maximum and single event levels (SELs) were also measured for each overflight, for comparison with published aircraft data. A “short circuit” was found due to an exposed vent pipe, which resulted in no transmission loss in the 100 Hz band. Appropriate recommendations were made.
Perceptive relevance of soundscape descriptors: a morpho-typological approach
Authors: Polack Jean-Dominique , Beaumont Jacuqes , Arras Christine , Zekri Mikael , Robin Benjamin
Published: May 2008

For assessing the validity of a morpho-typological classification of urban sounds with respect to sound assessment, factor analysis was applied to a database compiled in the city of Lyon and lead to a four-classes classification based on the number of lanes and whether a street is one-way or not. Free categorisation was then carried out on sound excerpts recorded in different sites corresponding to different classes. The main results are: a corpus of 42 h of five-channel recordings of a choice of sites from the classification at different times of the day; the validation of the relevance of the morpho-typological classification for perception; and a confirmation of the semantic oppositions between sources and background noise, as well as holistic and event sequences. Further, annoyance is controlled by the absence or the presence of human or nature sound sources, pleading for research toward automatic identification of sources. Last, categorisation confirms earlier investigations based on variance analysis: in narrow and large streets, traffic increase differently governs the increase of both noise level and annoyance.
Environmental management of a large construction site in a densely populated urban area: an innovative approach to noise and vibration mitigation
Authors: Masoero Marco , Bertetti Carlo Alessandro
Published: May 2008

An innovative approach to noise and vibration mitigation has been applied to the construction of a new underground railway. The aim is to overcome the difficulties in respecting noise level limits in densely populated areas, as specified by current legislation, even with state-of-the-art technology (e.g., low-emission machinery, noise barriers, etc.). The proposed approach aims at integrating the construction activity in the urban soundscape, placing maximum emphasis on construction organisation measures (e.g., construction activity scheduling and execution, training and information of contractor's personnel, etc.) and on communication and involvement of the exposed population. In this respect, two key figures have been identified: the first is an environmental engineer permanently assisting the construction manager in all the environmental impact issues; the second consists of a sample of population for which the subjective reaction to noise is monitored and fed back to the construction manager. Results are presented and discussed for one of the main construction sites in central Turin.
Processing of long-term acoustic measurements
Authors: Faiget Laurent , Plassat Benoit , Bloquet Stéphane , Aujard Christine
Published: May 2008

Many standards and European directives relative to noise are used to assess an acoustic situation, based on long-term indicators such as Lday, Lnight or Levening. These indicators are defined mainly as the mean yearly equivalent acoustic level on a particular part of the day. Acoustic measurements are performed on reference periods representative of the typical acoustic situation. An Oper@ monitoring system performed measurements for two years on several points. An acoustic database of the one-second integration time measurement was created. Different kinds of calculations were performed on these data, the variant being the measurement time considered. This study evaluates the convergence of the classic equivalent level with these long-term indicators.
Buildings thermal and acoustics insulation: friends or enemies
Authors: Roland Jacques
Published: May 2008

The increasing concern on climate changes and greenhouse gas accumulation has urged most of countries to enforce new thermal regulation to improve the energy efficiency of existing and new buildings. This improvement shall not at least induce a reduction of the acoustic comfort, and possibly increase it by a careful choice of products and a relevant design. The new products and technologies involve the building envelop insulation, the thermal bridges suppression, the improvement of air conditioning efficiency, and the renewable energy sources attached to the building. The author will review these new products and technologies and show what are the expected benefit or threat for the acoustic performance of buildings. This will include triple glazing, bulk insulating materials, natural fibrous materials, vacuum insulation panels, phase change materials, thermal bridge isolators, integrated photovoltaic cells, light weight construction, passive house concept, heat pumps, and air conditioning with heat exchangers.
Acoustic behavior of triple glazings
Authors: Rehfeld Marc , Fournier David
Published: May 2008

Making of triple glazings is the only way to still improve thermal performances of Insulating Glass Units. Possible ways with double glazings are already in use: increase the space between glasses, use low emissivity coatings and special gas with lower thermal conductivity as argon or krypton. Specific acoustic weak point of double glazings is the resonance between the two panes which works as a mass spring mass system, and coupling of eigenmodes of panes through the air (gas) cavity. These phenomena are of course still more important with triple glazings, as there are two resonances. The paper will give all comparative data concerning thermal and acoustic performances, and describe a way to achieve the same single number values of sound transmission loss with triple glazing that with double glazing by adding absorption in the gas cavities.
R+D for the integration of high acoustic-thermal performances in spanish building products
Authors: Fuente Marta
Published: May 2008

Many EU countries are introducing new national regulations aimed at complying with the European Directive “Energy Performance of Buildings” (EPBD). Subsequently, in Spain a new normative has been recently approved (CTE-HE), compiling new requirements for energy saving in buildings. In this framework, energy efficiency considerations will have an increasing impact on the design of buildings and the choice of materials and products. In the same way, the acoustical quality of dwellings in Spain is going to be guaranteed with the compliance of the new Spanish Building Regulation (CTE-HR). Searching a higher level of comfort in dwellings the CTE is increasing its requirements and is considering the building as a product itself. These new developments involve efforts and resources for the upgrading of the constructive materials and systems, demanding investments for R&D activities. Therefore manufacturers of the constructive sector in Spain are launching many innovative research strategies for the development of better products, addressing key factors for the energy efficiency of buildings.
Sound insulation of traditional roof constructions considering energy efficiency requirements
Authors: Mesterházy Beáta , Reis Frigyes , Szlávik Gábor
Published: May 2008

The efforts for energy efficiency result changes in building constructions, also in case of roof constructions. The most important constructional conclusion is the growth of the thickness of the heat insulating layer. Beside heat insulation, inner ventilation between the layers is the other important parameter, which has a great effect on sound insulation behaviour. In regular product information sheets, either in internet or in printed forms, the effect of these later parameter is not present and this way the laboratory data do not show the reality. For the purpose of modeling the reality, a new installation method has been developed, which considers the effects of ventilation usually used in our climate conditions. This new installation method has been realised and used in laboratory experiments. The results based on the new installation method approach the reality better and reflect the acoustical importance of the certain constructional components.
Sound transmission loss of vacuum insulation panels
Authors: Maysenhölder Waldemar
Published: May 2008

The sound transmission loss of a variety of vacuum insulation panels (VIP) has been measured in the laboratory. Core materials of the VIP include silica, polyurethane, micro fleece, and glass fibers. Mass law behavior and minima due to bending-wave coincidence and thickness resonance have been observed. Destroying the vacuum may reduce the sound insulation drastically. Since in practical applications the VIP need protection, the predominant interest lies in the transmission loss of multilayered assemblies, e.g., VIP sandwiched between aluminum plates. Calculations performed by the software LAYERS show that with additional “decoupling” layers (air, rubber) the coincidence dip can be avoided or shifted to higher frequencies, where it is less critical. Preliminary experimental realizations indicate the important role of a proper gluing of the layers. According to further LAYERS calculations, attachment of VIP to massive walls and protection by a plaster layer does not change the transmission loss of the wall appreciably, except for the VIP with the soft polyurethane core material.
Using high light reflectance acoustical ceilings to increase the energy efficiency of buildings
Authors: Bischel Marsha S. , Beakes William E.
Published: May 2008

Acoustical ceilings with white, highly light-reflecting surfaces can be used as an effective, passive means to significantly improve the energy efficiency of a space. When a ceiling with high light reflectance is coupled with an indirect lighting system, illumination can be increased by 20%, or the energy directly associated with lighting can be reduced by 20%. In addition, lower lighting loads can reduce cooling costs by 7%. A highly light reflective ceiling can also be used to reflect daylight into a space, increasing the amount of light in interior areas away from the windows by as much as 20%; alternatively, the surface area of windows may be reduced by 14% while maintaining the same illumination levels. In all cases, the increased reflectance of light allows the number of fixtures to be decreased, further increasing the savings related to both energy and maintenance. The percentage of energy savings associated with lighting is proportional to the percentage increase in the light reflectance value; therefore, even small increases in light reflectance provide increases in energy efficiency. When the acoustical performance of two products is comparable, light reflectance could be a critical differentiator in determining total building performance and occupant comfort.
High sound and thermal insulation constructions with dB-deck
Authors: Ingelaere Bart , Vermeir Gerrit , Wuyts Debby
Published: May 2008

The new Belgian requirements demand DnT,w⩾58 dB and L'nT,w⩽50 dB between apartments for enhanced acoustic comfort. At the same time the Energy Performance Regulations impose strict requirements for the thermal insulation between apartments. Higher demands on sound insulation can be realized in practice by using higher surface weights for walls and floors and by applying failure free floating floors. However requiring higher weights for floors is in contradiction with the technique of concrete hollow floor elements. A thermal and acoustical solution was found in the development of dB-deck, a prefab double floor element with intermediate supporting elastic pads, cutting structural vibration paths between superposed apartments. In combination with double walls without anchors (allowing for a high sound reduction index and no structural transmission in the horizontal sense), this construction technique allowed for DnT,w>63 dB and L'nT,w<47 dB without a floating floor in experimental setups This solution was developed by a team of the BBRI, KULeuven, and CDM for an important producer of hollow floor elements. This technique has now been used for real constructions. The paper presents technical details, the results of the acoustical measurements and the acoustical advantages and difficulties met in the construction of this apartment block.
The use of U50 to calculate the optimal absorption in a classroom
Authors: Nijs Lau , Rychtarikova Monika , Vermeir Gerrit
Published: May 2008

Common measures for the speech intelligibility predict increasing values with increasing absorption in empty classrooms. Measurements confirm this relation, so it seems as if an anechoic room is the best place to teach. However, there are two problems: the sound pressure level at the back row is too low when compared to the levels on the front row or when compared to the noise level caused by pupils plus ventilation systems. A simple method is proposed based on U50, which gives the relation between the sound energy from direct sound (from a teacher or a pupil) plus early reflections on one side and late reflections plus noise on the other. Barron's formula for the sound level decrease in a concert hall is included to predict the sound level drop through the classroom. Model results indicate that the absorption coefficient should be in the order of 20 to 30% if the signal to noise ratio is in the range between +5 to -5 dB. These values seem low, but measurements in existing classrooms show low signal to noise levels as well.
Jet noise prediction using RANS CFD input
Authors: Omais Magdi , Redonnet Stephane , Caruelle Bastien , Manoha Eric
Published: May 2008

In the present work, a volume source model based on the SNGR approach, first proposed by Bailly, has been implemented and developed for jet noise prediction purposes. This method presenting the advantage of providing unsteady three-dimensional turbulent data from a RANS computation, it shall be compatible with industrial development processes. First, the theoretical aspects of the original SNGR model were revisited. More particularly, analytical developments showed that considerable modifications were needed to take local flow effects into account while generating unsteady turbulent data. Moreover, the way to include anisotropy effects in the model, as originally proposed by Billson, was improved by using a nonlinear extension of Boussinesq approximation to recover the local Reynolds stress tensor. In a second step, the potentialities of the stochastic tool for jet noise simulations have been evaluated against existing numerical and experimental databases. In addition to that concern, its sensitivity to a slight modification of the RANS input data was studied. As a last step, the possibility of accounting for high frequency dynamics in reasonable CPU times has been deeply investigated. The main results obtained from this study show that the stochastic approach should be a promising method for future applications to industrial nozzle configurations.
Automatic segmentation of traffic noise
Authors: Mato-Méndez Fernando José
Published: May 2008

The state of the art in audio source separation reflects a growing interest towards developing tools oriented to speech and music applications. However, its application to the study of noise, and more specifically to the study of traffic noise, is scarce. The source separation in this work environment is a key process for subsequent classification and analysis, and has motivated the present research carried out. This paper is intended to present, therefore, the different strategies followed in the implementation of an automatic segmentator for traffic noise, focusing the research on two main aspects: The removal of components of noise unrelated with the sources of study and, by other side, the detection and separation of audio sources acquired. For this purpose, measures of traffic noise are made and results are analyzed for the running system, achieving a high level of performance in real work conditions.
The influence of meteorological conditions on noise propagation outdoors and sustainable planning of roads and motorways
Authors: Lebiedowska Barbara Joanna
Published: May 2008

Adequate road planning that allows for the separation of built-up areas and travel routes is one of the basic prevention strategies of hazards resulting from road usage. If possible, the roads should never be routed across cities and residential districts. However, if for some reason a busy road must be located near a built-up area, long-term meteorological conditions, characteristic of the area, must be examined prior to the execution of any work. Road planning on the basis of the analysis of the “rose of conditions favourable” to noise propagation will help minimise the road's negative acoustic influence on the adjacent buildings and facilities. The acoustic profile of two selected sites (in Poland and in France) is examined in the paper. Conditions favourable to propagation differ significantly in both cases depending on the position of the source-to-receiver direction in relation to the directions of the world
Assessment of military shooting noise
Authors: Boegli Hans , Wunderli Jean Marc , Brink Mark
Published: May 2008

The assessment of the impact of noise exposure on the population is a fundamental step in noise abatement. It includes the establishing of an exposure-response relationship and the setting of an impact threshold that specifies the protection level for the population and triggers eventually mitigating measures to reduce noise exposure. In Switzerland, the impact thresholds should be set so that, in the light of current scientific knowledge and experience, noise exposure below these thresholds will not seriously disturb the well-being of the population. For most current noise sources such as roads, railways and airports there already exist impact thresholds as part of the noise abatement legislation. Yet, no impact thresholds for military shooting grounds have been specified so far. Therefore a study was carried out in order to assess the impact of military noise exposure. The research included the calculation of noise exposure of eight military shooting grounds ranging from small infantry shooting ranges to expanded artillery and tank training facilities and a survey at over 1000 residents in the neighbourhood of these installations. Preliminary results suggest that although the responses of the population to military noise are rather dispersed, data should be sufficiently consistent to establish an exposure-response relationship.
Design and evaluation of novel barriers
Authors: Bamnios George , Rekanos Ioannis , Zacharias Konstantinos , Trochidis Athanasios
Published: May 2008

This work presents the results of a project for the design of novel noise barriers with improved performance. The aim of the project was twofold. First, to optimize the performance of barriers by appropriately modifying both the shape and the acoustical conditions at the edge to suppress the sound pressure. Second, to quantify the acoustic performance of the novel barriers both mathematically and experimentally in a standardized, well controlled process. The insertion loss of different types of barriers with modified edge shapes and acoustical conditions were investigated systematically in comparison with conventional ones using a method based on BEM. The comparison highlighted the influence of shape and edge configuration on barrier efficiency and allowed the design of novel barriers with optimal performance. The novel barriers were tested and their efficiency was quantified experimentally using the Maximum Length Sequence (MLS) technique, which offers the advantage of in-situ measurements in the presence of extraneous noise. The experimental results are shown to be in good agreement with the experiments. Based on the aforementioned procedure, a unified framework was established, witch allows the design of potentially improved noise barriers.
Nuisance control of leisure activities
Authors: Barti Robert
Published: May 2008

In Spain there are more than 345 000 leisure activities with more than 1.2 M jobs. This economical sector produces the 2.2% of the PIB overall Spanish economic production. Tourism is a big source of money for many Spanish cities. Leisure activities is the most common economic activity related with this sector. Typical Spanish good weather let's people to remain for a long time up to early morning in the streets. Human activity produces always noise. Acoustic noise control measurements uses dB(A) scale for evaluation. Low noise levels dB(A) has no correlation with acoustic perception of people because people can “follow” the rhythm of the music. Increase the TL of structures let's to reduce the noise from activities, but increasing the power amplifier the problem remains still in the same point. The solution checked is to use an acoustic limiter as a warranty of no contamination to neighbours from the activity. Some results about this technique are discussed in this paper. In order to solve a complain between neighbours an leisure activity, a political solution is more effective than technical solution is. The main objective is to set the correct balance between perception of sounds and acoustic comfort at home.
Perspectives for a strategical mapping of soundscapes
Authors: Memoli Gianluca , Licitra Gaetano , Cerchiai Mauro
Published: May 2008

The transposition of the European Noise Directive by Member States gives a new way to action plans of urban areas, underlying (article 6 and Annex III) that dose-effect relations should be used to assess the effect of noise on populations. Particular interest, in this sense, has the relationship between annoyance and perceived soundscape: it is now almost accepted that a higher annoyance is not always proportional to higher noise levels. This paper will demonstrate that a way to move from mapping noise exposure to a map of annoyance passes through the characterization of the soundscapes present on the territory. A numerical indicator (“slope”), derived from the time history of the measured sound/noise, will in fact be used to characterize the evolution along the day of the soundscapes present in the city of Pisa (I). In particular, “slope” (correlated to annoyance in previous studies) will be used to prepare a map of the annoyance in selected areas of Pisa: predicted annoyance will be to be compared with the one extrapolated by noise levels. Differences, similarities and their effects on action plans will be discussed.
Analysis and evaluation of noise reaction in open public spaces in Mexico City
Authors: German Miriam
Published: May 2008

Mexico City, with a population estimated in 19 millions, is part of one of the largest metropolitan areas in the world. Unfortunately, scientific work on urban noise in Mexico City is scarce. A study on people reaction to urban noise carried out in open public spaces of two different zones of Mexico City will be presented. A previous survey in those zones showed that the noise levels exceeded the values recommended by international organizations to protect public health and welfare. The general objective of the study to be presented was to identify the sound sources perceived by the pedestrians, and to evaluate their response to urban noise pollution in the two mentioned areas. The results show that for most of the people (a) urban noise is not considered a relevant aspect to improve the quality in the city, although urban noise has a negative effect on the decision of using open public spaces; (b) the people with knowledge of the negative effects of noise pollution are more annoyed; (c) vehicular traffic is the most annoying noise source, contributing significantly the public transportation; (d) one of the principal strategies to confront urban noise is to get used to it.
Perception of noise in suburban and urban areas
Authors: Paz Elaine C. , Zannin Paulo Henrique Trombetta T.
Published: May 2008

This work analyses, using a comparative approach, the environmental noise perception in the daily lives of inhabitants of a residential area, with that of a mixed (residential and commercial) area (downtown), in a large Latin America city. The goal was to confront an ideal urban environment with one acoustically polluted, as function of noise descriptors. Concomitant with the evaluation of noise perception (subjective analysis), noise levels were measured (objective analysis) in both areas. The single average equivalent noise level (Leq) found for downtown was 73 dB(A), and 53 dB(A) for the residential area. A random sample of the populations of both areas was taken, through a questionnaire. Questionnaire data was treated statistically through a factorial multivariate analysis. This analysis has generated three statistical indicators: time perception, atypical noise perception, and sources and disturbances. Over 50% of both populations sampled have the perception that high frequency noise levels are gradually increasing, with higher contribution from traffic noise. The dominant organic effects reported were irritability and loss of concentration ability, these last being precursors of hearing loss.
Reflection of sound from a forest: comparison of experimental data to scattering theory
Authors: Salomons Erik , Wunderli Jean Marc
Published: May 2008

Reflection of sound by a forest has been investigated by means of measurements near Thun in Switzerland. Sound pulses were generated at 50 and 150 m from the forest, and reflected sound was recorded at distances of 100, 200, and 300 m from the forest. By comparison with numerical calculations of reflection of sound from a hard wall, using a parabolic-equation model for sound propagation in an atmosphere with wind and temperature as recorded during the measurements, the attenuation of sound waves upon reflection at the forest was determined. It was found that the reflection attenuation decreases from about 20 dB at low frequency to about 10 dB at high frequency. The experimental results for the reflection attenuation are compared with results of a theoretical model for scattering of spherical sound waves by a single row of cylinders. The model employs an effective spacing between the cylinders, to account for trees that are not at the edge of the forest, i.e., inside the forest. The model results are in good agreement with the experimental results. The comparison indicates that the effective spacing decreases with decreasing frequency, as low-frequency waves penetrate deeper into a forest than high-frequency waves do.
Environmental noise reduction means of weapons
Authors: Pääkkönen Rauno
Published: May 2008

Noise from hand-held weapons is generated by their muzzle blast, the noise of the bullet in flight and on impact. The muzzle blast of almost all powder guns exceeds 140 dB near the ear of the shooter, which is considered to be able to generate a risk of hearing defects. The muzzle brake decreases recoil, but at the same time it forces the sound sideways and backwards. One novel aspect of noise attenuation is the use of active noise cancelling system at shooting ranges and in hearing protectors. The noise data has been collected on different shooting ranges in Finland. Both front and reflection types of suppressors were used. Silencers that attenuate noise to the sides and back have a significant effect, where as the noise to the front is not significantly attenuated because of the bullet noise. It is also possible to reach an attenuation of a few decibels of the maximum level of the muzzle blast with ANC headsets. The noise created by shotguns is the most significant source of environmental noise at many shooting ranges. It would be especially important to attain new ideas and innovations in the noise prevention of shotgun ranges.