Sound Pressure Level

The objective of this study is to assess the incidence of the urban noise at the facades of the Paraná State Court of Accounts "Tribunal de Contas do Estado do Paraná" (TCE-PR), located at the Civic Center of Curitiba, a planned government district and a heritage-listed area of great urban and cultural relevance. The TCE-PR buildings, officially designated as historical landmarks, present unique architectural features that must be preserved while addressing environmental noise challenges. The methodology integrates in situ measurements, following NBR 10151, with three-dimensional acoustic mapping following ISO 9613, enabling a detailed evaluation of noise incidence across the facades. The results indicate that the facades are subject to distinct noise level gradients, influenced by urban traffic dynamics and surrounding structures. These variations require different sound insulation strategies to ensure acoustic comfort while preserving the architectural and historical integrity of the buildings. The combined methodology provides a quantitative framework for optimizing façade insulation, preventing over-or under-dimensioning of acoustic treatments. Additionally, the use of predictive acoustic modeling has demonstrated the importance of tailored acoustic solutions for heritage buildings exposed to urban noise pollution.

Noise pollution is a phenomenon that affects many large cities and is caused by several factors, one of which is traffic noise due to the high population density in urban areas. This paper aims to investigate three retrofitting techniques to reduce traffic-induced noise on the main faç ade of the architectural department building at Cairo University. Initial physical measurements recorded a minimum noise level of 63.9 dB(A), exceeding World Health Organization (WHO) standards. The first technique explores geometry manipulation by altering the inclination angles (5° and 15°) of the faç ade protrusions. The second technique evaluates two sound-absorbing cladding materials: green wall systems and coarse concrete tiling. The third technique combines the two approaches, applying the cladding materials to the optimized angles. Using I-Simpa as a computational simulation tool, the sound pressure levels (SPL) resulting from each technique were analyzed. The results indicate that the base case scenario with a 0.75-meter protrusion achieved an average SPL reduction of 1.7 dB(A) with a green wall and 2.4 dB(A) with coarse concrete. However, implementing a combination of techniques-including increased protrusion, inclination, and surface treatment-proved more effective, achieving a maximum SPL reduction of 2.8 dB(A) from the highest recorded level. This study demonstrates the potential of integrated retrofitting strategies to address urban noise pollution effectively.

On New Year's Eve and some festivals, we encounter a great number of firecracker explosions. The peak sound pressure levels originating from the explosions can cause annoyance, loss of hearing, fire hazards, serious personal injuries, and even death. The immission of a peak sound pressure level at a given location due to an individual firecracker depends mainly on its sound power, on the distance from the explosion, and on the sound pressure distribution in the time and frequency domain. In this paper, some practical measurements have been performed over a New Year's Eve, and the results were compared with other days. A special emphasis is given to statistical aspects and the probability distribution function of peak sound pressure levels, originating from a great number of random firecracker explosions. Results have shown that the probability distribution closely follows the Rayleigh distribution, but, when the number of explosions per unit time is high enough, it tends to a Gaussian (normal) distribution.

We tested the ability of birds to detect and discriminate natural vocal signals in the presence of masking noise using operant conditioning. Masked thresholds were measured for budgerigars, Melopsittacus undulatus, and zebra finches, Taeniopygia guttata, on natural contact calls of budgerigars, zebra finches and canaries, Serinus canaria. Thresholds increased with increasing call bandwidth, the presence of amplitude modulation and high rates of frequency modulation in calls. As expected, detection thresholds increased monotonically with background noise level. Call detection thresholds varied with the spectral shape of noise. Vocal signals were masked predominantly by noise energy in the spectral region of the signals and not by energy at spectral regions remote from the signals. In all cases, thresholds for discrimination between calls of the same species were higher than thresholds for detection of those calls. Our data provide the first opportunity to estimate distances over which specific communication signals may be effective (i.e. their 'active space') using masked thresholds for the signals themselves. Our results suggest that measures of peak sound pressure level, combined with the spectrum level of noise within the frequency channel having the greatest signal power relative to background noise, give the most similar results for estimating a signal's maximum communication distance across a variety of sounds. We provide a simple model for estimating likely detection and discrimination distances for the signals tested here.

The vibration generated by railway traffic causes complaints not only about sensible vibration levels, but about significant noise levels in the building lying beside or above rail lines. Therefore numerical methods to predict the effect of train passbys are very important to possess and to develop. This paper presents a new numerical prediction method based on the Rayleigh radiation integral which al- lows us to calculate sound pressure levels inside a cavity when the normal velocity distribution along the boundary surfaces are known. For validation the method was compared to the Boundary Element Method by means of calculations on the- oretical rooms with theoretical velocity distributions along their walls. Beside these calculations, thorough measurements were carried out in buildings - mostly monolythic con- crete portal frame structure buildings. Synchronous, multi channel recordings of vibration and noise signals were performed. The results of the measurements and the simulatio...

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Hearing loss is one of the most common human impairments. It is estimated that by year 2015 more than 700 million people will suffer mild deafness. Most can be helped by hearing aid devices depending on the severity of their hearing loss. This paper describes the implementation and characterization details of a dual channel transmitter front end (TFE) for digital hearing aid (DHA) applications that use novel micro electromechanical-systems (MEMS) audio transducers and ultra-low power-scalable analog-to-digital converters (ADCs), which enable a very-low form factor, energy-efficient implementation for next-generation DHA. The contribution of the design is the implementation of the dual channel MEMS microphones and powerscalable ADC system. Keywords:-transmitter front end(TFE), digital hearing aids(DHA), ultra low power scalable ADCs, MEMS microphones I.

Vigorous homogeneous fluidization of 12‐nm silica particles was easily achieved by coupling aeration with vibration. Vibration (with frequency in the range of 30 to 200 Hz, and vibrational acceleration in the range of 0 to 5 g) was found to be necessary to achieve smooth fluidization. The minimum fluidization velocity, defined as the lowest gas velocity at which the pressure drop across the bed reaches a plateau, was approximately 0.3–0.4 cm/s, and essentially independent of the vibrational acceleration. However, the bed expanded almost immediately after the air was turned on, reaching bed expansions of three times the initial bed height or higher. Thus the bed appeared to exhibit a fluidlike behavior at velocities much lower than the minimum fluidization velocity. Fluidization of nanoparticles was achieved as a result of the formation of stable, relatively large, and very porous agglomerates. Practically no bubbles or elutriation of particles was observed. A fractal analysis combin...

The academic quality is strongly related the interest of students to the classes, as well as the interaction between them with their teachers. The problem that can disturb this formation is the noise interference, which could complicate the understanding of the classes developed within the school context. In a classroom, are considered noise, the sounds that disturb the speech understanding of teachers by students, or affect the verbal response given by students to the teacher. Are also considered noise, sounds that distract the concentration causing the lost of the focus in the class. The unwanted sounds can permanently damage the health of students and teachers because they need to raise the tone of voice, which may cause damage to your vocal cords and / or their hearing systems. The quality acoustics of classrooms is recommended by INMETRO by ABNT NBR 10152:1987, which specifies the sound pressure levels that case if they exceeded, impair the health and education in classrooms. T...

This paper proposes an approach for the determination of uncertainties related to sound pressure levels measured in accordance with procedures given in ISO 5130 for noise emitted by stationary road vehicles. This approach to assessing uncertainty is based on the international ...

Public Law 91-596, "Occupational Safety and Health Act of 1970," Dec. 29, 1970, stimulated interest in modeling the impacts of interior noise on employees, as well as the intelligibility of interior public-address and other speech intra-communication systems. The classical literature on this topic has primarily featured a statistical uniform diffuse-field model. This was pioneered by Leo L. Beranek in the 1950s, based on energy-density formulations at the former Bell Telephone (AT&T) Laboratories in the years from 1930 to 1950. This paper compares the classical prediction approach to the most recent statistical methods. Such models were developed in the late 1970s and included innovations such as consideration of irregularly shaped (e.g., L-shaped) interior room spaces and coupled spaces.

Testere ile kesme, talaşlı imalat proseslerinin ilk aşamasında yer alan ve metal, polimer, ağaç gibi farklı türden malzemelerin istenilen boylarda kesilmesine olanak sağlayan bir imalat yöntemidir. Bu işlem için endüstride genellikle şerit ve daire testere tezgâhları kullanılır. Yöntem talaşlı imalat prosesleri için kritik olduğundan, kesme işleminin verimi ve kesilen iş parçalarının yüzey kalitesi sonraki prosesler için büyük önem taşır. Yüzey kalitesi, talaşlı imalat yöntemleri ile üretilen iş parçalarının işleme verimliliğinin belirlenmesinde anahtar bir rol oynar. Yüzey kalitesi, kesme parametrelerinin optimizasyonu ve takım tezgâhlarına eklenen çeşitli fonksiyonlar ile artırılabilmektedir. Bu çalışmada, literatürde işlenebilirliği zor olarak tanımlanan AA 6082 alaşımının testere ile kesilmesinde talaş tahliyesini kolaylaştırmak adına delik delme proseslerinde kullanılan, kesme hızında değişiklik olmadan ilerleme oranının işleme sürecinde kesintiye uğratılmasına olanak sağlayan gagalama yöntemine benzer bir teknik kullanılmıştır. 3 farklı gagalama süresi (0-300-600 ms), 4 farklı gagalama mesafesi (0-4- 6-8 mm), 2 farklı kesme hızı (105-130 m/dk) ve 2 farklı ilerleme oranı (90-110 mm/dk) deney parametreleri ile kesme işlemleri gerçekleştirilmiştir. Deneysel bulgular, numunelerin ön ve arka yüzeylerinin pürüzlülük değerleri incelenerek değerlendirilmiştir. Yöntemin doğruluğu ve her bir deney parametresinin yüzey pürüzlülüğü üzerindeki etkileri anova (varyans) analizi ile incelenmiştir. Sonuçlar gagalama fonksiyonunun AA 6082 malzemesinin testere ile kesilmesinde yüksek seviyeli deney parametrelerinin yüzey kalitesini iyileştirebileceğini göstermiştir.

We conducted 58 playback experiments with free-ranging African elephants in Etosha National Park, Namibia, to estimate the distance over which some of their low-frequency calls are audible to other elephants. We broadcast pre-recorded elephant calls to elephants that were 1.2 and 2.0 km from the speaker while making simultaneous video and audio recordings of their behavior. In order to reduce the risk of habituation, we used a variety of call types as stimuli. Elephants responded to playbacks at both 1.2 and 2.0 km, with a full response consisting of the elephant vocalizing, lifting and spreading its ears, remaining motionless in this position (‘freezing’), moving the head from side to side (‘scanning’) and, in the case of males responding to female estrous calls, orienting to and finally walking 1 km or more towards the loudspeaker. We analyzed our data quantitatively for three of these responses. The occurrence of each behavior increased substantially immediately after playbacks. ...

A wider and wider spread of timber structures entail a stronger and stronger use of of these building elements in Mediterranean weather environments. CLT technology is nowadays taken in consideration with special attention on account of the various benefits that it can allow in terms of shortened time of laying and attainable performance. The aim of this work consists of evaluating passive acoustic requirements with specific attention to impact sound insulation.

This paper reports the performance improvement of micromachined piezoelectric microspeakers that are audible in open air according to the geometrical parameters. The sound pressure level (SPL) of the microspeaker fabricated with a piezoelectric ZnO film is even more enhanced due to the carefully designed process conditions and electrode shapes. The SPL of the fabricated microspeakers, which have a square electrode, shows more than 50 dB from 400 Hz to 20 kHz; the highest SPL is about 94 dB at 9.5 kHz with 5 Vpp sinusoidal input biases and 3 mm distances from the fabricated microspeakers to the reference microphone.

An analysis of the acoustical and flowfield environment for the scaled 1-pound-force (lbf) thrust tabletop motor was performed. The jet characterization is based on computational fluid dynamics (CI_©) in conjunction with Kirchhoff surface integral formulation and compared with correlations developed for measured rocket noise and a pressure fluctuation scaling (PFS) method. Comparisons are made for the overall sound pressure levels (OASPL's) and spectral dependence of sound pressure level (SPL).

From 203 cases of low-frequency complaints a random selection of twenty-one cases were investigated. The main aim of the investigation was to answer the question whether the annoyance is caused by an external physical sound or by a physically non-existing sound, i.e. low-frequency tinnitus. Noise recordings were made in the homes of the complainants, and the complainants were exposed to these in blind test listening experiments. Furthermore, the low-frequency hearing function of the complainants was investigated, and characteristics of the annoying sound was matched. The results showed that some of the complainants are annoyed by a physical sound (20-180 Hz), while others suffer from low-frequency tinnitus (perceived frequency 40-100 Hz). Physical sound at frequencies below 20 Hz (infrasound) is not responsible for the annoyance -or at all audible -in any of the investigated cases, and none of the complainants has extraordinary hearing sensitivity at low frequencies. For comparable cases of low-frequency noise complaints in general, it is anticipated that physical sound is responsible in a substantial part of the cases, while low-frequency tinnitus is responsible in another substantial part of the cases.

From 203 cases of low-frequency complaints a random selection of twenty-one cases were investigated. The main aim of the investigation was to answer the question whether the annoyance is caused by an external physical sound or by a physically non-existing sound, i.e. low-frequency tinnitus. Noise recordings were made in the homes of the complainants, and the complainants were exposed to these in blind test listening experiments. Furthermore, the low-frequency hearing function of the complainants was investigated, and characteristics of the annoying sound was matched. The results showed that some of the complainants are annoyed by a physical sound (20-180 Hz), while others suffer from low-frequency tinnitus (perceived frequency 40-100 Hz). Physical sound at frequencies below 20 Hz (infrasound) is not responsible for the annoyance -or at all audible -in any of the investigated cases, and none of the complainants has extraordinary hearing sensitivity at low frequencies. For comparable cases of low-frequency noise complaints in general, it is anticipated that physical sound is responsible in a substantial part of the cases, while low-frequency tinnitus is responsible in another substantial part of the cases.

From a group of 203 cases of low-frequency-noise complaints a random selection of twenty-one cases were investigated. The main aim of the investigation was to answer the question whether the annoyance is caused by an external physical sound or by a low-frequency tinnitus. Noise recordings were made in the homes of the complainants, and the complainants were exposed to these recordings from their own home in blind test listening experiments. Furthermore, the low-frequency hearing function of the complainants was investigated, and characteristics of the annoying sound was matched. The results showed that some of the complainants are annoyed by a physical sound (20-1 80 Hz), while others suffer from low-frequency tinnitus (perceived frequency 40-100 Hz). Physical sound at frequencies below 20 Hz (infrasound) is not responsible for the annoyance -or at all audible -in any of the investigated cases, and none of the complainants has extraordinary hearing sensitivity at low frequencies. For comparable cases of low-frequency noise complaints in general, it is anticipated that physical sound is responsible in a substantial part of the cases, while low-frequency tinnitus is responsible in another substantial part of the cases.

EL DERECHO AMBIENTAL INTERNACIONAL DECLARACIONES INTERNACIONALES QUE SE VINCULAN CON UN DERECHO A UN AMBIENTE SANO DECLARACIONES INTERNACIONALES QUE SE VINCULAN EL DERECHO DEL DESARROLLO SOSTENIBLES CARACTERÍSTICAS DEL DERECHO AMBIENTAL PRINCIPIOS DEL DERECHO AMBIENTAL CONTAMINACIÓN ACÚSTICA EFECTOS DE LA CONTAMINACIÓN ACÚSTICA LAS PRINCIPALES CAUSAS DE CONTAMINACIÓN POR RUIDO RUIDO COMO OBJETO DEL DERECHO AMBIENTAL RUIDO COMO VULNERADOR AL DERECHO A LA SALUD RUIDO COMO VULNERADOR AL DERECHO A LA INTIMIDAD CONSTITUCIÓN POLÍTICA DEL PERÚ DE 1993 LEY GENERAL DEL AMBIENTE – LGA N° 28611 DECRETO SUPREMO N° 085-2003 – PCM LEY ORGÁNICA DE MUNICIPALIDADES – LOM N° 27972 PROCESOS JUDICIALES EN DEFENSA DEL AMBIENTE EL CENTRO HISTÓRICO DE AREQUIPA RECONOCIDO COMO PATRIMONIO CULTURAL DE LA HUMANIDAD DESCRIPCIÓN DE LA IMPLEMENTACIÓN DE LA ORDENANZA MUNICIPAL N° 12 – 1999 MPA ACTAS DE INSPECCIÓN PREVENTIVA Y SANCIONES EMITIDAS DESDE LA ENTRADA EN VIGOR DE LA ORDENANZA MUNICIPAL N° 269-2014-MPA E...

Today, finish surface materials with hard, unruffled, or smooth surfaces are preferred in the tiling, walls, and ceilings of restaurants and dining halls because of their hygienic and easy-cleaning characteristics. In this context, in restaurants and dining halls that have sound-reflecting surfacesare also classified as reverberant rooms where talking sounds are added to the background noise level; thus, the noise level in the setting increases gradually, and speech intelligibility is affected unfavorably. In the context of this study, the pre-assessment of the dining hall of Ankara University Medical School faculty members was completed by using measurements, simulations, and estimation methods; because the appropriate acoustic conditions that comply with regulations, international standards, and suggestions in the literature were not met, suggestions were developed for acoustic treatment. Because of feasibility issues, improvements were implemented only on the walls, which was one...

In individuals with Parkinson's disease (PD), respiratory muscle weakness and rigidity, bradykinesia of abdominal muscles and stiffness of the chest wall, affect the respiratory component of voice intensity due to reduced pulmonary capacity and airflow needed to vibrate the vocal folds. It may be possible to improve voice production by strengthening respiratory muscles. The purpose of this study was to evaluate the effects of inspiratory and expiratory muscle training on voice production outcomes in individuals with PD. Method. Thirty-one participants with PD were randomly allocated to three study groups (control group n = 10, inspiratory training group, n = 11, and expiratory training group, n = 11). The inspiratory and expiratory group performed a home-based inspiratory and expiratory muscle training program, respectively (five sets of five repetitions). Both groups trained six times a week for 2 months using a progressively increased resistance. The control group performed expiratory muscle training using the same protocol and a fixed resistance. Phonatory measures, maximum inspiratory/expiratory pressure, and spirometric indexes were assessed before and at 2 months after training. Results. Differences in peak subglottic pressure were moderate (d = 0.59) between expiratory and inspiratory groups, large between inspiratory and control groups (d = 1.32), and large between expiratory and control groups (d = 1.96). Differences in maximum phonation time were large (d = 1.26) between inspiratory and control groups, moderate (negative) between expiratory and inspiratory groups (d = -0.60), and moderate between expiratory and control groups (d = 0.72). Differences in peak sound pressure level were large (d = 1.27) between inspiratory and control groups, trivial between expiratory and inspiratory groups (d = -0.18), and large between expiratory and control groups (d = 1.10). Conclusions. Inspiratory muscle training is effective in improving maximum phonation time, and expiratory muscle training is more effective for improving peak subglottic pressure, and peak sound pressure level in individuals with PD.

Cutting tool wear degrades the product quality in manufacturing processes. Monitoring tool wear value online is therefore needed to prevent degradation in machining quality. Unfortunately there is no direct way of measuring the tool wear online. Therefore one has to adopt an indirect method wherein the tool wear is estimated from several sensors measuring related process variables. In this work, a neural network-based sensor fusion model has been developed for tool condition monitoring (TCM). Features extracted from a number of machining zone signals, namely cutting forces, spindle vibration, spindle current, and sound pressure level have been fused to estimate the average flank wear of the main cutting edge. Novel strategies such as, signal level segmentation for temporal registration, feature space filtering, outlier removal, and estimation space filtering have been proposed. The proposed approach has been validated by both laboratory and industrial implementations.

Noise reduction is one of the highest prior target for diesel engine because of the more and more strict engine noise limits, diesel engine noise has been drawing significant attention from automotive manufacturers. To effective reduce the noise level of a diesel engine the first step is the identification of different engine noise sources. The design and development of modern diesel engines is marked by a reduction in exhaust gas emissions and increase in specific power and torque.Exhaust noise is one of the major contributors to noise from vehicles powered by internal combustion engine. For the same power rating, diesel engines are noisier than gasoline engines, since the combustion characteristics of diesel engines produce more harmonics than slower combustion of gasoline.This paper reviews different noise sources and methods are available for noise reduction of diesel engine.

The magnocellular theory is a prominent, albeit controversial view asserting that many reading disabled (RD) individuals suffer from a speci®c impairment within the visual magnocellular pathway. In order to assess the validity of this theory we tested its two basic predictions. The ®rst is that a subpopulation of RD subjects will show impaired performance across a broad range of psychophysical tasks relying on magnocellular functions. The second is that this subpopulation will not be consistently impaired across tasks that do not rely on magnocellular functions. We de®ned a behavioural criterion for magnocellular function, which incorporates performance in ¯icker detection, detection of drifting gratings (at low spatial frequencies), speed discrimination and detection of coherent dot motion. We found that some RD subjects (six out of 30) had impaired magnocellular function. Nevertheless, these RD subjects were also consistently impaired on a broad range of other perceptual tasks. The performance of the other subgroup of RD subjects on magnocellular tasks did not differ from that of controls. However, they did show impaired performance in both visual and auditory nonmagnocellular tasks requiring ®ne frequency discriminations. The stimuli used in these tasks were neither modulated in time nor brie¯y presented. We conclude that some RD subjects have generally impaired perceptual skills. Many RD subjects have more speci®c perceptual de®cits; however, the `magnocellular' level of description did not capture the nature of the perceptual dif®culties in any of the RD individuals assessed by us.

Extracellular adenosine triphosphate (ATP) has profound effects on the cochlea, including an effect on the regulation of the endocochlear potential (EP). Noise-induced release of ATP into the endolymph activates a shunt conductance mediated by P2X 2 receptors in tissues lining the endolymphatic compartment, which reduces the EP and, consequentially, hearing sensitivity. This may be a mechanism of adaptation or protection from high sound levels. As inaction of such a process could contribute to hearing loss, this study examined whether the action of ATP on EP changes with age and noise exposure in the mouse. The EP and the endolymphatic compartment resistance (CoPR) were measured in mice (CBA/CaJ) aged between 3 and 15 months. The EP and CoPR declined slightly with age with an associated small, but significant, reduction in auditory brainstem response thresholds. ATP (100-1,000 μM) microinjected into the endolymphatic compartment caused a dosedependent decline in EP correlated to a similar decrease in CoPR. This was blocked by pyridoxal-phosphate-6-azophenyl-2′,4′-disulfonate, consistent with a P2X 2 receptormediated shunt conductance. There was no substantial difference in the ATP response with age. Noise exposure (octave-band noise 80-100 decibels sound pressure level (dBSPL), 48 h) in young animals induced an upregulation of the P2X 2 receptor expression in the organ of Corti and spiral limbus, most noticeably with the 90-dB exposure. This did not occur in the aged animals except following exposure at 90 dBSPL. The EP response to ATP was muted in the noiseexposed aged animals except following the 90-dB exposure. These findings provide some evidence that the adaptive response of the cochlea to noise may be reduced in older animals, and it is speculated that this could increase their susceptibility to noise-induced injury.

While simulation (digital twins) in Architectural Acoustics has advanced significantly due to cloud computing, novel algorithms, and machine learning, progress in research and development of innovative Acoustic diffusers for applications in recording and performance arts has been limited for the past 2 decades. Recording and performance arts is and has always been interwoven with acoustics, which are primary surfaced-based (2D) and not portable (semi-permanent). While previous studies have generally examined the diffusivity of a lower order sonic crystal in an anechoic chamber, It is far removed from practical real-world applications. The author has put forward a novel higher order sonic crystal hybrid based on Costas Array-irido, to investigate the potential of being employed as a volumetric diffuser is a valid application. This proposed sonic crystal offers a level of portability and modularity that surpasses traditional surface diffuser counterparts (i.e. QRD and skyline), while also serving as an effective noise barrier. The paper details the generation of the Costas Array, showcases both theoretical predictions and experimental results related to the proposed sonic crystal's performance as a volumetric diffuser and noise barrier. Audio samples from evaluation sessions that explore different configurations, placements, and applications involving musicians from diverse genres, instrumentations, and demographics are included for interpretation.

This paper reports some of the results of a DISIA research project, sponsored by the Italian Environment Ministry, named "Definition of the acoustic recovery goals in urban areas". In more detail, the authors developed two computer codes covering different tasks: the first is a simplified acoustic model, capable of mapping the sound pressure level (L A,eq,day or L A,eq,night ) over large portions of a town or even on the whole urban area. The second is an highly detailed numerical code, based on the new Pyramid Tracing algorithm, more suited for detailed analysis of small areas, where acoustic recovery is needed. In this paper the first computer program is described, among with the experimental measurements undertaken for building the input data-base, and with the validation procedure. An application example is then reported. In the following paragraphs the main goals of the research project are first described, followed by the results of the experimental characterization of urban noise sources. Then the computing algorithm is explained in detail, and some aspects of the user's interface and of the interaction with other computer programs (CAD, GIS and mapping utilities) are described. The results of the verification procedure, by comparison with experimental measurements in some test sites, are reported, and eventually an application example in the urban area of Mestre (Venice) is shown. Questo lavoro riporta alcuni dei risultati ottenuti nell'ambito di un progetto di ricerca DISIA, promosso dal Ministero dell'Ambiente, denominato "Individuazione degli obiettivi di risanamento acustico nelle aree urbane". In maggior dettaglio, gli autori hanno sviluppato due programmi per computer aventi scopi diversi: il primo è un modello di propagazione acustica semplificato, in grado di mappare il livello sonoro (L A,eq,diurno o L A,eq,nott. ) su larghe porzioni di territorio urbano. Il secondo è un codice numerico di dettaglio, basato sul nuovo algoritmo di Pyramid Tracing, più indicato per l'analisi particolareggiata di aree limitate, ove è necessario progettare interventi di bonifica acustica. In questo articolo viene descritto il primo programma di calcolo, assieme con i rilievi sperimentali utilizzati per la caratterizzazione delle sorgenti di rumore urbano. Viene poi spiegato in dettaglio l'algoritmo di calcolo, e vengono illustrate l'interfaccia utente del programma e la sua interazione con altri programmi (CAD, GIS, programmi di mappatura). Vengono infine presentati i risultati della procedura di validazione del programma, ottenuti per confronto con rilievi sperimentali in alcuni siti di prova, ed un esempio di applicazione nell'area urbana di Mestre (VE). Sia nella fase di zonizzazione acustica del territorio urbano, che nella successiva fase di gestione del problema del rumore nelle aree urbane, si sente la necessità di disporre di un sistema informatico in grado di fornire la mappatura acustica del territorio. Questa può essere derivata integralmente da rilievi sperimentali, ma può essere ottenuta viceversa anche mediante l'impiego di modelli numerici, molti dei quali disponibili in Europa anche in forma di raccomandazioni ufficiali dei Ministeri competenti in vari Paesi. La superiorità della soluzione basata sul modello numerico consiste soprattutto nel fatto che essa consente il ricalcolo immediato della nuova situazione per effetto di modifiche al Piano Urbano del Traffico (P.U.T.), per effetto della edificazione di nuove costruzioni, o per la realizzazione di opere di contenimento delle emissioni sonore. Tuttavia in passato è risultato evidente come l'impiego dei modelli di calcolo, anche i più raffinati, porti a stime della rumorosità estremamente disperse in assenza di qualsiasi forma di taratura del modello mediante rilievi sperimentali: in occasione di un Round Robin fra modelli di calcolo europei, alla cui organizzazione ha partecipato uno degli autori [1], è risultato che anche in casi geometricamente molto semplici si verificano differenze di 4-5 dB(A) fra i vari programmi di calcolo, e che nel caso la situazione geometrica si complichi anche di poco, queste variazioni arrivano fino a 12 dB(A). Si noti poi che le differenze riscontrate non riguardano solo la modellazione di fenomeni di propagazione a lunga distanza (che in ambito urbano sono comunque poco rilevanti), ma anche la vera e propria emissione da parte delle sorgenti sonore. Considerando che il Round Robin di cui sopra teneva in considerazione solo sorgenti di rumore legate al traffico stradale fluente (tipo autostrada), ci si aspetta una situazione ancora peggiore applicando simili modelli semplificati di emissione in campo urbano, in presenza di traffico non fluente, e magari anche in presenza di linee ferroviarie che attraversano la città. Si è pertanto deciso di realizzare un sistema di calcolo che privilegiasse l'accuratezza nella stima delle emissioni sonore, descrivendo con grande dettaglio i tipi di sorgente e le loro modalità di emissione. E' stata dunque realizzata una imponente campagna di rilievi sperimentali, onde disporre di un data-base di emissione, tarato sulla realtà italiana, e comunque sempre modificabile ed aggiornabile in funzione di ulteriori rilievi. In tal modo il modello di calcolo non contiene al suo interno le informazioni legate all'emissione sonora, che sono viceversa disponibili come dati di ingresso, eventualmente modificabili onde adattare il funzionamento del modello a realtà urbane diverse da quelle in cui è stata condotta la sperimentazione. Ai fini di realizzare con tempi di calcolo ragionevoli la mappatura di una intera città, si è scelto poi di impiegare i dati di emissione come input di un algoritmo di calcolo molto semplificato, tenuto conto del fatto che all'interno delle aree urbane non sono solitamente molto importanti i fenomeni di propagazione su lunga distanza. E' ovviamente possibile (e necessario) disporre di un modello molto più raffinato allorchè, anzichè mappare l'intera città, si decide di studiare in dettaglio un singolo gruppo di edifici, onde ad esempio verificare l'efficacia di diversi sistemi di contenimento del rumore: a questo scopo è stato realizzato un diverso programma di calcolo, di cui si relaziona a parte [2]. Affinchè l'operazione di mappatura dell'area urbana possa venire intrapresa in tempi ragionevoli ed a costi contenuti, è necessario che la base cartografica ed i dati di input del modello siano disponibili in forma informatizzata: pertanto il programma di mappatura del livello sonoro nelle aree urbane, che è stato battezzato CITYMAP, è stato dotato di idonea interfaccia software verso i sistemi CAD comunemente usati per applicazioni di G.I.S. (Geographical Information Services). Tramite questo collegamento, è possibile creare all'interno dei sistemi CAD l'assieme di dati geometrici (tracciato delle strade e dei binari, sorgenti di tipo industriale), agganciare alle entità geometriche i dati di emissione (traffico stradale e ferroviario, emissione delle sorgenti industriali) ed ottenere all'uscita del modello di calcolo una mappatura isolivello acustico perfettamente sovrapponibile alla cartografia digitale. Tutte queste operazioni sono possibili senza abbandonare l'ambiente multitasking di MS Windows, che funge da elemento di collegamento trasparente ai vari programmi. E' ovvio come queste possibilità siano utili nella fase di classificazione del territorio di un comune in zone acustiche ai sensi del DPCM 1 marzo1991 e della nuova Legge Quadro sull 'Inquinamento Acustico (L. 26 ottobre 1995, n. 447): diviene infatti possibile porre a confronto diretto, all'interno del software di mappatura acustica, la cartografia che riporta i limiti di rumorosità con quella che riporta i livelli effettivamente esistenti sul territorio. E' possibile così ottenere automaticamente una carta dei superamenti, in cui vengono evidenziate con diversi colori le zone in cui la rumorosità è superiore al limite proposto. Sul-

During the process of European integration the question arose how a standard could be created to assess qualitative and quantitative effects deriving from the development of transport infrastructures. The issue gets an even higher emphasis in case of valuation ...

This paper assesses a measurement method that seeks to provide information on the directional flow of energy in a space. Impulse responses on orthogonal Cartesian axes are derived through convolution of the received signals of a Soundfield microphone and the original test signal. The impulse responses are processed in Matlab to produce a spherical plot of energy level over 5 ms timeframes. Further analysis is possible through third octave filtering of the energy time curves. The results are plotted providing a visual analysis tool for assessment of the directional information associated with the reflection pattern, contained within the impulse response of a room.

Recognizing conspecifics individually is paramount in shaping animal societies, and vocal signals can play an important role in this process. Humans and some other species identify individuals by integrating information from different sensory modalities. This ability can facilitate stable relationships, kin recognition, and cooperative interactions. Studies of individual recognition in wild animals remain rare. Here, we present experimental evidence that wild greater sac-winged bats, Saccopteryx bilineata, a species with stable social groups, high roost fidelity, and a preference for well-lit day-roosts, recognize individual group members. In many species, including bats, individuals produce distress calls when physically constrained by a predator. We show that distress calls of S. bilineata encode individual signatures. Further, we conducted playback experiments at the day-roosts to test for individual recognition. We used a violation-of-expectation paradigm in which the subject is presented with information for individual identification aligning or conflicting with one another. When individual recognition occurs, the subject may show heightened attention to conflicting information or the plausible association. Remarkably, roosting bats only approached the source of a distress call under plausible conditions—when the supposed caller was absent from the roost. When confronted with an impossibility—the supposed caller was in the roost and its voice simultaneously came from elsewhere—bats ignored the playback entirely. This striking ability to detect and reject such inconsistencies reveals a high level of cognitive sophistication, as these bats reconcile what they see or smell with what they hear to assess the reality of a situation.

In industrial plants noise is a major threat to the mental and physical health of employees. The risk increases more due to the presence of high noise sources and the presence of too many employees in textile industry plants. This paper aims to predict the consequences of variables that may arise in the plants for acoustic improvement in textile industry plants. For this purpose, scenario plants have been created according to architectural properties and source-transmission path-receiver characteristics. The acoustic analyses of the scenario plants were performed in the ODEON Auditorium, and A-weighted sound pressure level (LA), noise reduction (NR), and reverberation time (RT) were determined. From the data, prediction equations were created with a multiple linear regression (MLR) model. To test the prediction equations, acoustic measurements were made, and acoustics improvements were carried out at a textile industry plant located in Türkiye. When the obtained results, the success, validity, and reliability of the prediction method are provided. In conclusion, the effect of architectural properties and the surface absorption on acoustic improvements in the textile industry was revealed. It was emphasized that prediction methods can be used to determine the effectiveness of interventions that can be applied in different facilities and can be improved in future studies.

Large reverberant chambers have been used for several decades in the aerospace industry to test larger structures such as solar arrays and reflectors to qualify and to detect faults in the design and fabrication of spacecraft and satellites. In the past decade some companies have begun using direct near field acoustic testing, employing speakers, for qualifying larger structures. A limited test data set obtained from recent acoustic tests of the same hardware exposed to both direct and reverberant acoustic field testing has indicated some differences in the resulting structural responses. In reverberant acoustic testing, higher vibration responses were observed at lower frequencies when compared with the direct acoustic testing. In the case of direct near field acoustic testing higher vibration responses appeared to occur at higher frequencies as well. In reverberant chamber testing and direct acoustic testing, standing acoustic modes of the reverberant chamber or the speakers and spacecraft parallel surfaces can strongly couple with the fundamental structural modes of the test hardware. In this paper data from recent acoustic testing of flight hardware, that yielded evidence of acoustic standing wave coupling with structural responses, are discussed in some detail. Convincing evidence of the acoustic standing wave/structural coupling phenomenon will be discussed, citing observations from acoustic testing of a simple aluminum plate. The implications of such acoustic coupling to testing of sensitive flight hardware will be discussed. The results discussed in this paper reveal issues with over or under testing of flight hardware that could pose un-anticipated structural and flight qualification issues. Therefore, it is of paramount importance to understand the structural modal coupling with standing acoustic waves that has been observed in both methods of acoustic testing. This study will assist the community to choose an appropriate testing method and test setup in the planning stages.

The Goldstein-Ruban theory has been extended within the quasi-parallel framework of Zavol'skii el al. to study the acoustic receptivity of compressible boundary layers. We consider the receptivity produced in a region of localized, small-amplitude variation in the surface temperature and compare it with the receptivity that is induced through a similar mechanism by a variation in the suction velocity at the surface. The orientation of the acoustic wave can have a significant impact on the receptivity process, with the maximum receptivity at a given sound-pressure level produced by upstreamoriented acoustic waves. At sufficiently low Math numbers, the variation of receptivity with the acoustic-wave orientation can be predicted analytically and is the same for both surface suction and surface heating. However, as a result of the acoustic refraction across the mean boundary layer, the above dependence can become complex and dependent upon the type of surface nonuniformity. The results also suggest that the receptivity caused by temperature nonnniformities may turn out to be more significant than that produced by the mean-flow perturbations associated with strip suction. of the viscous-inviscid interactive Tollmien-Schlichting mode (TS) (Ryzhov and Zhuk 1986, Smith 1989) which dominates the primary instability of two-dimensional boundary layers at subsonic and moderately supersonic speeds. Consequently, the wavelength reduction mechanisms previously identified by Goldstein (1983, 1985), and (1985) are also directly relevant to the generation of the viscous-inviscid interactive modes in compressible boundary layers.

This paper presents a numerical investigation of an active structural acoustic control strategy for coupled aircraft-style bays. While structural coupling can destabilize or limit the performance of some model-based decentralized control systems, fullycoupled centralized control strategies are impractical for typical aircraft containing several hundred bays. An alternative is to use classical rate feedback with matched, collocated transducer pairs to achieve active damping. Unfortunately, due to the conservative nature of this strategy, stability is guaranteed at the expense of achievable noise reduction. Therefore, this paper describes the development of a combined control strategy using robust active damping in addition to a high-authority controller based on linear quadratic Gaussian (LQG) theory. The combined control system is evaluated on a tensioned, two-bay model using piezoceramic actuators and ideal point velocity sensors. Transducer placement on the two-bay structure is discussed, and the advantages of a combined control strategy are presented.

A decentralized LQG-based control strategy is designed to reduce low-frequency sound transmission through periodically stiffened panels. While modern control strategies have been used to reduce sound radiation from relatively simple structural acoustic systems, significant implementation issues have to be addressed before these control strategies can be extended to large systems such as the fuselage of an aircraft. For instance, centralized approaches typically require a high level of connectivity and are computationally intensive, while decentralized strategies face stability problems caused by the unmodeled interaction between neighboring control units. Since accurate uncertainty bounds are not known a priori, it is difficult to ensure the decentralized control system will be robust without making the controller overly conservative. Therefore, an iterative approach is suggested, which utilizes frequency-shaped loop recovery. The approach accounts for modeling error introduced by n...

Experimental demonstration of active vibration and structural acoustic control using shape memory alloy (SMA) hybrid composites [C. A. Rogers, in Proceedings of the International Congress on Recent Developments in Air and Structure Borne Sound and Vibration (to be published)] has provided the motivation for investigating new control schemes and developing more accurate models. This paper will briefly describe newly developed constitutive models for shape memory alloy actuators and the hybrid material system. A general dynamical model for laminated SMA hybrid composite beams and plates will be presented with several theoretical results. A new structural acoustic model for laminated composite plates [Liang et al., J. Sound Vib. (to be published)] will be briefly described and the potential for active structural acoustic control using SMA hybrid composites demonstrated by numerical simulation.

Spoilers are panels mounted on the suction surface of aircrafts wings. Their main function is to slow the aircraft down during landing. In this article, numerical simulations of the flow around a wing airfoil with spoiler have been carried out using the software Ansys Fluent. It is of supercritical airfoils category, NASA SC (2) -0610. The main objective of this research is to calculate the drag, lift and pressure coefficients at different spoiler angles of deflections in order to explain the mechanism of the aircraft braking and lift spoiling when the spoiler is deflected during landing and to calculate the corresponding radiated tonal noise. The results show that the pressure increases in front of the spoiler while behind the spoiler, it decreases significantly because of flow separation. The pressure differences between front and back spoiler surfaces leads to an increase in the form drag and thus creating the braking on the aircraft. The other effect of the spoiler is to spoil the lift. This is a result of the increased pressure on the upper surface in front of the spoiler which causes a reduction in the lift coefficient and pushes the aircraft down, the lift coefficient is found negative and equal to -0.4313 for a spoiler angle of deflection 70°. The dominant frequency of the vortex shedding has been calculated and found equal to 29 Hz. This frequency is expected to appear and to be dominant in the wing vibrations and noise signals. The aerodynamics noise generated by the deflection of the spoiler at an angle of 70° is finally computed using the Ffowcs-Williams and Hawking (FWH) aeroacoustics analogy. It has been found that the radiated noise is a tonal noise in its nature because its principle source is the vortex shedding and its dominant frequency equal to the frequency of vortex shedding, around 29 Hz. The Sound Pressure Level (SPL) main pic arrives to 120 dB at a frequency of almost 29 Hz for a receiver located at a distance of 2 m above the airfoil trailing edge.

During the process of European integration the question arose how a standard could be created to assess qualitative and quantitative effects deriving from the development of transport infrastructures. The issue gets an even higher emphasis in case of valuation ...

The present experimental study has been conducted to evaluate the effect of different developed acoustic enclosures on the noise emission of a small generator set fuelled by natural gas. The sound signals of generator without enclosure and covered by developed enclosures were measured in front of the generator exhaust at five electric loading conditions (0%, 25%, 50%, 75% and 100% load). The sound signal was measured according to SAE J1074 test procedure. The recorded digital sound signals were converted to frequency domain using Fast Fourier Transform (FFT) algorithm. The results revealed that the simple enclosure (SE) and modified enclosures were effective to attenuate the generator noise at frequencies greater than 800 Hz and 250 Hz, respectively. The acoustic performance in attenuating the generator noise for the semi-covered modified enclosure (SME) and fully covered modified enclosure (FME) was better than for the SE enclosure. The acoustic performance of all enclosures was re...

Assessment of Closed-Loop Control Using Multi-Mode Sensor Fusion For a High Reynolds Number Transonic Jet 1 KERWIN LOW, BAS-MAN ELHADIDI, MARK GLAUSER, Syracuse University -Understanding the different noise production mechanisms caused by the free shear flows in a turbulent jet flow provides insight to improve "intelligent" feedback mechanisms to control the noise. Towards this effort, a control scheme is based on feedback of azimuthal pressure measurements in the near field of the jet at two streamwise locations. Previous studies suggested that noise reduction can be achieved by azimuthal actuators perturbing the shear layer at the jet lip. The closed-loop actuation will be based on a low-dimensional Fourier representation of the hydrodynamic pressure measurements. Preliminary results show that control authority and reduction in the overall sound pressure level was possible. These results provide motivation to move forward with the overall vision of developing innovative multi-mode sensing methods to improve state estimation and derive dynamical systems. It is envisioned that estimating velocity-field and dynamic pressure information from various locations both local and in the far-field regions, sensor fusion techniques can be utilized to ascertain greater overall control authority.

To accurately estimate the noise at a signalized intersection, it is necessary to precisely reproduce the traffic volume, signal cycle and traffic noise for each vehicle behavior and driving state. Precise reproduction requires considerable effort, such as continuous calculations of vehicles and the setting of parameters such as engine speed, engine load and velocity. A simple method that involves using A-weighted sound power levels (L WA ) under nonsteady running conditions has already been proposed for estimating noise at signalized intersections in a previous paper. In this study, the authors developed two simple methods for predicting noise in which the effects of acceleration and deceleration by signals is reflected. One method is based on a microsimulation traffic model, in which equivalent continuous A-weighted sound pressure levels (L Aeq ) is calculated by adding the noise of vehicles passing a green signal and the noise of vehicles decelerating and stopping at a red signal then accelerating when the signal turns green. The other method is even simpler and involves the assumption that an intersection zone is an unsteady running section and that L WA for a nonsteady running section is larger than that for a steady running section. Noise predicting by the three simple methods is compared with actual measurements at 10 sites. The two new methods had slightly improved accuracy relative to the measured results.