Showing papers in "Building Acoustics in 2003"
TL;DR: In this article, the effects of classroom noise on children's academic performance and annoyance due to classroom noise levels are discussed. But the authors highlight inconsistencies and discrepancies between the results of various studies and highlight some current acoustic standards for classrooms.
Abstract: This paper reviews research on issues relating to the effects of noise on children at school. Areas covered include factors affecting speech intelligibility in the classroom; the effects of environmental and classroom noise on children's academic performance; children's annoyance due to noise; and surveys of classroom noise levels. Consistencies and discrepancies between the results of various studies are highlighted. The paper concludes by outlining some current acoustic standards for classrooms.
333 citations
TL;DR: A catalogue of noise barrier profiles is provided; identifying the relative acoustic benefits of each and the physical principles on which they operate and the likely effects of ground and atmospheric conditions on their absolute acoustic performance.
Abstract: During the past four decades, extensive research has been carried out on different noise barrier shapes using analytical and physical modelling as well as full scale testing. This paper reviews traffic noise barrier research and its findings to date. It provides a catalogue of noise barrier profiles; identifying the relative acoustic benefits of each and the physical principles on which they operate. The likely effects of ground and atmospheric conditions on their absolute acoustic performance are described. The types of barriers which are commonly used in practice and those deserving further attention are highlighted. Based on the findings of previous work, recommendations are made on possible areas of further research.
54 citations
TL;DR: In this article, the authors review the practice and theory behind base isolation, and discuss some recent developments in modelling base-isolated buildings with a view to predicting isolation performance, which is becoming increasingly common as pressure grows to construct high-quality buildings on existing urban sites.
Abstract: Many buildings close to railway tunnels are built on steel springs or rubber bearings to isolate them from the ground-borne vibration. This base isolation of buildings has been employed since the 1960s and is becoming increasingly common as pressure grows to construct high-quality buildings on existing urban sites. This paper reviews the practice and theory behind base isolation, and discusses some recent developments in modelling base-isolated buildings with a view to predicting isolation performance.
25 citations
TL;DR: In this article, the authors concluded the analysis of the results of an acoustic survey carried out on nine Romanesque churches in Apulia (Italy) by taking into account both room-average values and individual position values of monaural and binaural acoustic parameters measured according to ISO 3382.
Abstract: This paper concludes the analysis of the results of an acoustic survey carried out on nine Romanesque churches in Apulia (Southern Italy), described in detail in a previous paper. The study was performed taking into account both room-average values and individual position values of monaural and binaural acoustic parameters, measured according to ISO 3382. First the effect of architectural parameters on reverberation time was investigated, showing that volume and materials play an important role. Then room-average values of the other acoustic parameters were investigated, showing that some are mostly correlated with reverberation time and others with total acoustic absorption. Analysis of individual location values showed that monaural parameters can be expressed as functions of the source-receiver distance, and one or two of the following parameters: room volume, total absorbing area, mean absorption coefficient, total length and reverberation time. Furthermore, it was demonstrated that individual positio...
22 citations
TL;DR: In this paper, the sound reduction index of lightweight panels with stiffeners is calculated using the wave approach applied to an infinite thin plate line connected to periodically spaced beams and excited in flexure by a single or random (diffuse field) incident plane acoustical wave.
Abstract: The sound reduction index of lightweight panels with stiffeners is calculated using the wave approach applied to an infinite thin plate line connected to periodically spaced beams and excited in flexure by a single or random (diffuse field) incident plane acoustical wave. The reaction forces and moments at the line connections are calculated from the flexural and torsional line impedance of the beams. The finite size of the panel is taken into account using a spatial windowing technique applied to the infinite panel. The case of two stiffened panels with a cavity in between and no structural connections between panels is also considered using the same approach; using SEA, the structural flanking path at the panel boundaries through any receiving structure can also be taken into account. Comparisons to measured results are given and discussed.
22 citations
TL;DR: A survey of the available theoretical models of the spatial distribution of the most significant acoustical parameters has been conducted, and the models most suitable for religious buildings have been applied to the churches selected.
Abstract: At the present time, music performances frequently take place in ancient religious buildings, and significant problems related to acoustic quality may occur. Measurement results obtained in 10 historically significant churches in the city of Genova, are examined. Experimental data obtained from research literature on auditoria and churches has been compared with the experimental results. A survey of the available theoretical models of the spatial distribution of the most significant acoustical parameters has been conducted, and the models most suitable for religious buildings have been applied to the churches selected. A comparison between theoretical models and experimental data is presented. A case study on the effects of permanent and non permanent acoustical treatment, without significantly changing the architectural characteristics, is presented for one of the churches selected. The results of the measurements, at various phases of the acoustical treatment, and some software simulations are presented.
21 citations
TL;DR: In this paper, the impact of a dome on reverberation time was investigated using a scale model study of a typical mosque and the results show how the parameter is affected and indicate how the phenomenon might be quantified.
Abstract: Though the importance of domes in worship buildings has been recognised since ancient times, their acoustic effects have not been entirely addressed by acoustics researchers. In addition to the known detrimental effects of late reflections and echoes, more complicated behaviour can be expected as a result of the coupling of the dome volume to the rest of the room. This investigation is focused on the impact of a dome on reverberation time. This is done using a scale model study of a typical mosque. The results show how the parameter is affected and indicate how the phenomenon might be quantified.
17 citations
TL;DR: This paper will review the development of Schroeder diffusers over the last three decades and suggest solutions to overcome the limitations of the original concepts.
Abstract: Schroeder diffusers revolutionised the design of scattering surfaces when they were invented in the 1970s. For the first time diffusers with defined acoustic performance could be easily designed. Since their inception, much has been learnt about the performance of the surfaces. Limitations of the original concepts have been studied, and solutions found to overcome many of these. This paper will review the development of this technology over the last three decades.
11 citations
TL;DR: It is proposed that an appropriate approach to the development of propagation models could be based upon specular reflections for the lower orders of reflections and diffuse reflections for higher orders of reflection.
Abstract: The nature of noise propagation through the urban fabric is not well understood and this reflects the difficulty in obtaining good quality data. The most promising approach to developing urban noise prediction models is computer simulation. Reflections from building facades are a mixture of specular and diffuse. However, as the order of reflection increases the relative fraction of energy reflected purely specularly will decrease and the reflection characteristics will resemble those of the pure diffuse case. It is proposed that an appropriate approach to the development of propagation models could be based upon specular reflections for the lower orders of reflections and diffuse reflections for higher orders of reflection. An alternative statement of the above is that the specular approach would be most appropriate for modelling near field propagation whilst the diffuse approach might be more appropriate for modelling mid and far field propagation. Two approaches to the development of diffuse prediction models have been identified. The radiosity method would allow the investigation of the effect of the disposition of individual buildings on noise propagation but would be computationally demanding if applied to large scale studies. Conversely, an approach based upon the classical diffusion equation is potentially capable of being applied to large scale studies but will not yield any local detail. It is suggested that both approaches might be suitable for incorporating into a comprehensive model for far field urban noise propagation.
11 citations
TL;DR: It is proposed that low frequency noise/vibration problems are best tackled by a combination of acoustic and microseismic methods, rather than using each method in isolation.
Abstract: It is proposed that low frequency noise/vibration problems are best tackled by a combination of acoustic and microseismic methods, rather than using each method in isolation. A new integrated method was devised and it was demonstrated that ‘ the whole is greater than the sum of the parts’ . The benefits and versatility of the new method are illustrated with reference to a case study. Unmanned monitoring took place at several houses near to an industrial site, using a multi-channel recording technique. Comparison of various components of the sound and vibration fields in each house was then carried out, which allowed various propagation paths to be distinguished. A range of further signal processing analyses was also employed to aid source determination.
9 citations
TL;DR: A statistical method for calculation of the acoustical parameters of lambertian enclosures (that is, enclosures with diffusely reflecting boundaries) is presented and shows that the method is reliable, flexible, and that computation times are low.
Abstract: A statistical method for calculation of the acoustical parameters of lambertian enclosures (that is, enclosures with diffusely reflecting boundaries) is presented. The theory considers the distribution of sound particles over the boundaries of the enclosures. The method includes the familiar Kuttruff Integral Equation. A homogeneous Markov Chain of first order is obtained through the time discretisation of the equations. Applications of this method are demonstrated for the case of a long enclosure and for the case of a real-shaped room. Decay calculations as well as steady-state sound distributions are obtained. The results show that the method is reliable, flexible, and that computation times are low.
TL;DR: Although the early studies of spatial impression focused on the importance of reverberant sound, recent investigations reveal that late-arriving sound from the side of the listener is more important for creating a strong sense of listener envelopment (LEV), so the question is: “Is diffusion over-emphasized?”
Abstract: The prominence of diffusion in auditorium acoustics is commonly acknowledged in the literature, but neither objective measure nor subjective description indicates how it should be defined. Since we know the early sound plays an important part in the subjective success of a concert hall, several acoustical parameters for acoustical design such as EDT, tI, C80, G80, LFE, IACCE, etc. were developed in relation to the early reflections. A sound field composed of a few discrete reflections is of course non-diffuse even in a hall with plenty of surface diffusers. These diffusers may be relevant to the late reverberant sound field, which contributes to the acoustical quality of a hall and will be considered as dependent on the degree of diffusion. Compared with RT60, EDT is a better indication of perceived reverberance, and the quality of reverberant sound may not be that significant to the hall acoustics. Although the early studies of spatial impression focused on the importance of reverberant sound, recent inv...
TL;DR: In this paper, the influence of static pressure and temperature on sound reduction indices, impact sound pressure levels and sound reduction index, and relative installation noise levels is investigated. But the effect of temperature and static pressure on sound power radiated by a vibrating structure is not compensated by any other mechanism.
Abstract: The influence of static pressure and temperature on sound reduction indices, impact sound pressure levels, improvements of impact sound pressure levels and sound reduction indices, and relative installation noise levels is investigated. Theory revealed a systematic influence on sound reduction index and normalized impact sound pressure level. Firstly, the sound power radiated by a vibrating structure is directly proportional to the sound impedance in air and therefore to static pressure and temperature to the power of -0.5. Secondly, the sound pressure produced in a room by a sound source also depends on sound impedance, i.e. on static pressure and temperature. Since the excitation of a test specimen is not influenced by static pressure or temperature, the two effects are not compensated by any other mechanism, thus temperature and static pressure also influence sound reduction index and normalized impact sound pressure level. Experimental verification involved measurement of sound reduction index in a small test suite at static pressures between 307 and 970 hPa. Measurement results for single-shell structures showed the expected behaviour, whereas results for double-shell structures revealed a considerable scatter with a tendency towards even larger temperature and static pressure influences. For comparison of the acoustic properties of building elements, it is therefore advisable to introduce a normalized sound reduction index and a normalized impact sound pressure level, with both referred to reference conditions of static pressure and temperature. Improvements in impact sound pressure levels and sound reduction index, and relative installation noise levels are determined from changes in sound level differences. Since each difference is influenced in the same manner by meteorological conditions, the resulting improvement is independent of static pressure and temperature, as long as the differences were determined under the same meteorological conditions.
TL;DR: In this article, the acoustic behavior of two building systems, a traditional concrete structure and an innovative one involving expanded polystyrene (EPS) elements have been compared using field measurements.
Abstract: The acoustic behaviour of two building systems, a traditional concrete structure and an innovative one involving expanded polystyrene (EPS) elements have been compared using field measurements. The results indicate that the airborne sound insulation is very similar for both construction methods, whereas impact sound insulation is better for the innovative system. The improvement obtained by introducing polyethylene foams in floating floor constructions has also been investigated for the EPS system using field measurements. Also, the impact sound insulation improvement obtained with two different polyethylene foams has also been analysed by performing laboratory experiments. Whilst both materials are adequate for this application, results indicate that the non cross-linked foam has a better performance.
TL;DR: The basic ideas of the GUM will be outlined and then applied to different modeled sound fields, and the results obtained with the linearised model usually used will be compared to exact results.
Abstract: Within the scope of quality management, the determination of measurement uncertainties is increasingly gaining importance. In this context the 'Guide to the Expression of Uncertainty in Measurement' (GUM) provides the physical and mathematical concept and fundamentals. It can be applied to all physical measurements. However, in measurements of pressure levels in sound fields in room or building acoustics, the relative uncertainties can be very large. The question is what implications this has for the calculation of uncertainties. The basic ideas of the GUM will be outlined and then applied to different modeled sound fields. The results obtained with the linearised model usually used will be compared to exact results.
TL;DR: In this article, the influence of the sound radiation from surfaces is examined from a prediction of structure-borne sound from a multiple coherent output spectrum, which represents common elements of all input vibration signals.
Abstract: The influence of the sound radiation from surfaces is examined from a prediction of structure-borne sound. The level of structure-borne sound due to environmental ground vibration is shown from a Multiple Coherent Output Spectrum, which represents common elements of all input vibration signals. The use of the Multiple Coherent Output Divided Spectrum at each surface is examined. A parameter is proposed which shows the contribution of structure-borne sound from the each surface of the room. The theory is considered for a system consisting of six speakers equivalent to the six surfaces of the room, and prediction compared with experimental results.