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  • 1.
    Ljunggren, Fredrik
    Luleå University of Technology, Department of Civil, Environmental and Natural Resources Engineering, Operation, Maintenance and Acoustics.
    A new technique to reduce vibration in lightweight floors2003In: Noise & Vibration Worldwide, ISSN 0957-4565, E-ISSN 2048-4062, Vol. 34, no 10, p. 10-15Article in journal (Refereed)
    Abstract [en]

    Lightweight floor constructions often suffer from annoying vibration. Long span floor are especially vulnerable with dynamic properties that yield both springiness due to low stiffness and resonant vibration due to poor damping. A new method, that treats resonant vibration, applicable to floors with resilíent ceiling, is presented in this study. By using a piece of strategically located visco-elastic material connected to the ceiling joists, which is designed using a finite element model for an optimal position and size, it is demonstrated that the damping of the floor is increased. The results show that the damper is extremely efficient to reduce vibration of the type where floor and ceiling are oscillating out of phase to each other. The device also affects in phase modes like the fundamental one, but to a lower extent.

  • 2.
    Ljunggren, Fredrik
    Luleå University of Technology, Department of Civil, Environmental and Natural Resources Engineering, Operation, Maintenance and Acoustics.
    Changed sound properties due to minor construction changes in a lightweight building2008In: Journal of the Acoustical Society of America, ISSN 0001-4966, E-ISSN 1520-8524, Vol. 123, no 5, p. 3763-Article in journal (Other academic)
    Abstract [en]

    This paper relates to building acoustic measurement inside a two-story office house. The construction, which is known as lightweight, is prefabricated in volumes at a factory and is then transported to the building yard for assembling. It is build up of a wooden frame with particle boards and plaster boards attached. The building consists of a number of nominally, or almost nominally, identical rooms with assumed identical sound properties. In the projection stage, the construction was slightly modified in some of the rooms in order to see in what way the sound properties would be affected. In total eight impact sound pressure level measurements and eight sound reduction index measurements were performed and analysed for the different setups.

  • 3.
    Ljunggren, Fredrik
    Luleå University of Technology, Department of Civil, Environmental and Natural Resources Engineering, Operation, Maintenance and Acoustics.
    Floor vibration: dynamic properties and subjective perception2006Doctoral thesis, comprehensive summary (Other academic)
    Abstract [en]

    This thesis covers research in the floor vibration field. Although lightweight steel framed constructions have been in focus, many results are applicable to floors in common and to some extent also to vibrations in general. Whether a floor is treated as "good" or "bad" by the occupants is an interaction of a) the dynamic properties of the floor and of b) human vibration perception. Both these factors are covered. Two steel framed floors were tested in laboratory condition with respect to its dynamic. Modal testing was used to obtain the modal parameters, i.e. natural frequencies, damping and mode shapes. Both floors were tested for numerous set-ups where for example the effect of different supports, top layers, ceiling joists and simulated partitions were investigated. For one of the floors, subjective opinions were collected for correlation with the measured data. The research of floor dynamic has lead to a creative new method that utilizes strategically positioned small pieces of visco-elastic material to increase the damping of the floor. It was found out that this economic and proportionally easy method significantly increases the damping for some specific type of modes. The human vibration sensitivity was tested in a new developed motion simulator. Absolute threshold values for single sinusoidals were tested in the frequency range of 5-31.5 Hz. For validation of the test setup, the results were compared with data from other similar studies. The obtained thresholds agreed satisfactorily with previously reported results. More innovated tests were performed concerning multiple frequency signals of two to five discrete frequency components. The results show that a signal's composition in terms of number of frequency components and their mutual amplitude relation significantly affect the subjective perception. Therefore, it can be argued that multiple natural frequencies of a floor should be considered when it comes to design rules. This is in opposition to many floor design criteria of today since these often rely upon the fundamental frequency only. A prediction model, where the acceptance is calculated as a function of the frequency weighted total acceleration amplitude in combination with the fundamental frequency is suggested. The presented model does take into account the presence of possible multiple response frequencies.

  • 4.
    Ljunggren, Fredrik
    Luleå University of Technology, Department of Civil, Environmental and Natural Resources Engineering, Operation, Maintenance and Acoustics.
    Improved sound insulation in module based timber framed buildings2008In: BNAM 2008 - Joint Baltic-Nordic Acoustics Meeting: Proceedings, 2008Conference paper (Refereed)
    Abstract [en]

    This paper describes an ongoing research project at Luleå University of Technology. The project deals with lightweight building systems based upon industrial prefabricated building volumes. The size of each module can be approximately 8x4 m2. Although the technique has the same typical drawbacks as other similar lightweight building constructions, i.e. poor sound and vibration performance at low frequencies, the concept invites to some unique solutions which could benefit the sound properties. The overall objective of the project is to find new/modified economical constructions which enable module based wooden buildings to fulfill stated building codes with reasonable margin. Various constructions, and thereby various sound properties, should be offered according to the customers demand. The project contains a number of sub studies which are presented.

  • 5.
    Ljunggren, Fredrik
    Luleå University of Technology, Department of Civil, Environmental and Natural Resources Engineering, Operation, Maintenance and Acoustics.
    Is it necessary to measure impact sound insulation from 20 Hz in lightweight multi-storey buildings?2014Conference paper (Refereed)
  • 6.
    Ljunggren, Fredrik
    Luleå University of Technology, Department of Civil, Environmental and Natural Resources Engineering, Operation, Maintenance and Acoustics.
    Long-term effects of elastic glue in lightweight timber constructions2011In: Proceedings of Forum Acusticum: 6th Forum Acusticum 2011;Aalborg;27 June 2011through1 July 2011, 2011, p. 1685-1688Conference paper (Refereed)
    Abstract [en]

    The effect of using elastic glue in between a timber construction's two floor layers - gypsum board and particle board - was investigated. In a new timber based building, the impact sound insulation was reduced by 2 dB when elastic glue was introduced in the production. To find out the long-term effects, six different elastic glues was involved in a laboratory test in which layers of floor plaster board and particle board, 0.5x0.6m2, were glued together. The test has so far been running for two years. A majority of the glues showed significant reduction in modal damping ratio after a couple of months while a couple of them, to high extent, have maintained their properties over time.

  • 7.
    Ljunggren, Fredrik
    Luleå University of Technology, Department of Civil, Environmental and Natural Resources Engineering, Operation, Maintenance and Acoustics.
    Optimering av ljudegenskaper hos volymtillverkade flerfamiljshus i trä: inverkan av mindre konstruktionsändringar2008In: Bygg & Teknik, ISSN 0281-658X, Vol. 100, no 3, p. 15-20Article in journal (Other (popular science, discussion, etc.))
  • 8.
    Ljunggren, Fredrik
    Luleå University of Technology, Department of Civil, Environmental and Natural Resources Engineering, Operation, Maintenance and Acoustics.
    Reduction of resonant vibrations in lightweight floors2002Licentiate thesis, comprehensive summary (Other academic)
  • 9.
    Ljunggren, Fredrik
    Luleå University of Technology, Department of Civil, Environmental and Natural Resources Engineering, Operation, Maintenance and Acoustics.
    Sound insulation in a six-storey volume based timber building equipped with elastic layers2010In: Proceedings of the 17th international congress on sound & vibration, 2010, Vol. 2, p. 846-851Conference paper (Other academic)
    Abstract [en]

    Lightweight multi-storey timber buildings based upon prefabricated volumes is a technique of increasing interest. A great advantage is that the technique encourages the use of elastic layers in between floors and also to have a construction where the upper floor is disconnected from the lower ceiling besides at the boundaries. But, in accordance to similar constructions, it might be troublesome to obtain good sound insulation, particularly at low frequencies.In this paper the airborne sound reduction and impact sound pressure level are investigated. The object is a six-storey apartment house which is characterised by the amount of storeys which is large with respect to the building technique. The demands then increase regarding the overall constructional design as well as the design of the elastic layers in between floors which have to be stiffer. It is therefore of great importance to study whether these parameters cause deterioration regarding sound properties.

  • 10.
    Ljunggren, Fredrik
    Luleå University of Technology, Department of Civil, Environmental and Natural Resources Engineering, Operation, Maintenance and Acoustics.
    Using elastic layers to improve sound insulation in volume based multi-storey lightweight buildings2009In: 38th International Congress and Exposition on Noise Control Engineering 2009: INTER-NOISE 2009 ; Ottawa, Canada, 23 - 26 August 2009 / [ed] J. Stuart Bolton, Red Hook, NY: Curran Associates, Inc., 2009, p. 252-257Conference paper (Refereed)
    Abstract [en]

    Lightweight buildings often suffer from poor sound insulation, especially at low frequencies. The volume technique in which sections are being assembled to form a complete building, are well suited for the use of elastic layers in between floors as an action to improve the sound performance.Upon the floor construction's load-bearing beams, one or multiple layers of boards are normally attached. Particle boards and/or plaster boards are installed using screws and/or glue. In the case of using glue solely, there is a potential to improve the sound insulation if glue with elastic properties is used instead of a traditional one which will harden completely.Results from using different kinds of elastic layers between floors as well as different kinds of board glues, all tested on identical constructions, are presented in terms of airborne sound reduction and impact sound pressure level.

  • 11.
    Ljunggren, Fredrik
    Luleå University of Technology, Department of Civil, Environmental and Natural Resources Engineering, Operation, Maintenance and Acoustics.
    Vibration measurements of a steel joist floor system2002Report (Other academic)
    Abstract [en]

    A steel joist floor, prefabricated in sections, is investigated with respect of vibration levels. Measurements are performed using one, two and four elements joined together. Different modifications to the floor are tested to see in what way they affect the vibrations. An extra damper has a considerable effect, especially to a certain kind of mode shapes. Introducing lumped supports at the long-sides give further improvement. Changing the direction of the floor gypsum boards give a minor effect.

  • 12.
    Ljunggren, Fredrik
    et al.
    Luleå University of Technology, Department of Civil, Environmental and Natural Resources Engineering, Operation, Maintenance and Acoustics.
    Edfast, Fredrik
    Luleå tekniska universitet.
    Experimental work to increase the damping in a resilient ceiling2002Report (Other academic)
    Abstract [en]

    In order to find solutions that can increase the damping of a lightweight steel joist floor, a series of small-scale experiments on a piece of resilient ceiling is performed. Two different types of "extra dampers" using a visco-elastic material are tested where one of them, working by shearing, seems to be effective. The measured material properties are compared with ideal properties simulated by a FE-model. The stiffness of the used visco- elastic material shows good agreement but has a lower damping constant than ideal.

  • 13.
    Ljunggren, Fredrik
    et al.
    Luleå University of Technology, Department of Civil, Environmental and Natural Resources Engineering, Operation, Maintenance and Acoustics.
    Simmons, Christian
    Simmons akustik och utveckling, Chalmers Teknikpark, Gothenburg, Sweden.
    Airborne sound insulation between dwellings, from 50 vs. 100 Hz: a compilation of Swedish field surveys2018In: Applied Acoustics, ISSN 0003-682x, Vol. 133, p. 58-63Article in journal (Refereed)
    Abstract [en]

    It has for long been debated whether 50 or 100 Hz is the proper lower frequency limit when evaluating airborne sound insulation between dwellings. Although 100 Hz is the lowest third-octave band within most regulations, there is an ongoing interest in paying more attention to lower frequencies. In Sweden, evaluation from 50 Hz became mandatory already in 1999 wherefore unique experiences are available by now. In this paper, extensive data in terms of field measurements and questionnaire surveys from in total 46 building objects of various constructions have been compiled. A number of single number quantities, standardized by ISO as well as alternatives, are compared concerning their correlation against the subjectively rated annoyance responded by the residents. The statistical evidence for a 50 Hz limit was found to be small considering the total database but when the lightweight buildings were analyzed by their own, the importance of frequencies below 100 Hz became clearer. The overall recommendation is to include frequencies from 50 Hz in order to achieve good sound protection against a broad variety of sound sources, including music and other possible items generating low frequencies.

  • 14.
    Ljunggren, Fredrik
    et al.
    Luleå University of Technology, Department of Civil, Environmental and Natural Resources Engineering, Operation, Maintenance and Acoustics.
    Simmons, Christian
    Simmons akustik & utveckling.
    Hagberg, Klas
    WSP, Gothenburg.
    Findings from the AkuLite project: Correlation between measured vibro-acoustic parameters and subjective perception in lightweight buildings2013In: Internoise 2013: Noise Control for Quality of Life, Innsbruck, 2013, Vol. 2, p. 1578-1585Conference paper (Refereed)
    Abstract [en]

    Various research aspects on sound and vibrations in lightweight buildings are covered by the Swedish research programme AkuLite. One of the most important topics has been to find out to what extent objective measured parameters correlate with subjective opinions from people living in multifamily houses. Typical questions to be pointed out are: Do existing ratings like R'w (+C50-1350) and L'n,w (+CI,50-2500) correlate well enough to the tenants' perception? Can other measureable parameters be found that show better agreement? Are the often used frequency limits of 100Hz or 50Hz low enough? Can any significant differences be seen when comparing lightweight buildings with concrete buildings? Extensive sound and vibration measurements have been performed in numerous buildings of varying construction including lightweight timber or steel based framing, cross laminated timber and concrete. In general frequencies from 20 Hz have been covered. Questionnaires have been distributed to the tenants where they were asked to give their opinion on a number of adequate questions related to sound and/or vibration perception. The results from the measurements and from the questionnaires have then been compiled, followed by a comprehensive statistical analysis in order to see the degree of correlation between them.

  • 15.
    Ljunggren, Fredrik
    et al.
    Luleå University of Technology, Department of Civil, Environmental and Natural Resources Engineering, Operation, Maintenance and Acoustics.
    Simmons, Christian
    Luleå University of Technology.
    Högberg, Klas
    WSP Acoustics, Ullevigatan 19, 41140 Gothenburg.
    Correlation between sound insulation and occupants’ perception: Proposal of alternative single number rating of impact sound2014In: Applied Acoustics, ISSN 0003-682X, E-ISSN 1872-910X, Vol. 85, p. 57-68Article in journal (Refereed)
    Abstract [en]

    Traditionally, multi-family houses have been constructed using heavy, homogenous materials like concrete and masonry. But as a consequence of the progress of lightweight building systems during the last decades, it has been questioned whether standardized sound insulation evaluation methods still are appropriate.An extensive measurement template has been applied in a field survey where several vibrational and acoustical parameters were determined in ten Swedish buildings of various constructions. In the same buildings, the occupants were asked to rate the perceived annoyance from a variety of natural sound sources. The highest annoyance score concerned impact sounds, mainly in the buildings with lightweight floors.Statistical analyses between the measured parameters and the subjective ratings revealed a useful correlation between the rated airborne sound insulation and Rw′+C50–3150 while the correlation between the rated impact sound insulation and Ln,w′+CI,50–2500 was weak. The latter correlation was considerably improved when the spectrum adaptation term with an extended frequency range starting from 20 Hz was applied. This suggests that frequencies below 50 Hz should be considered when evaluating impact sound in lightweight buildings.

  • 16.
    Ljunggren, Fredrik
    et al.
    Luleå University of Technology, Department of Civil, Environmental and Natural Resources Engineering, Operation, Maintenance and Acoustics.
    Simmons, Christian
    Simmons akustik och utveckling.
    Öqvist, Rikard
    Luleå University of Technology, Department of Civil, Environmental and Natural Resources Engineering, Operation, Maintenance and Acoustics.
    Correlation between sound insulation and occupants’ perception: Proposal of alternative single number rating of impact sound, part II2017In: Applied Acoustics, ISSN 0003-682x, Vol. 123, p. 143-151Article in journal (Refereed)
    Abstract [en]

    A previous Swedish research project indicated the potential need for evaluating impact sound insulation from 20 Hz in buildings with lightweight constructions. This is a discrepancy compared to the commonly used frequency intervals starting from 50 or 100 Hz. The statistical significance of this groundbreaking suggestion was however not satisfactorily strong since the result was based upon a limited number of building objects.

    The scope of the present paper is to secure the previous study by adding additional objects to the underlying database, thereby increasing the confidence of the results. The methodology is to perform impact sound insulation measurements in apartment buildings of various construction types and to perform questionnaire surveys among the residents. The measured sound insulation is compared to the subjective rating by the occupants in order to find the parameter giving the highest correlation with respect to frequency range and weighting.

    The highest correlation was found when the impact sound insulation was evaluated from 25 Hz using a flat frequency-weighting factor. Frequencies below 50 Hz are of great importance when evaluating impact sound insulation in lightweight constructions

  • 17.
    Ljunggren, Fredrik
    et al.
    Luleå University of Technology, Department of Civil, Environmental and Natural Resources Engineering, Operation, Maintenance and Acoustics.
    Simmons, Christian
    Simmons akustik och utveckling.
    Öqvist, Rikard
    Luleå University of Technology, Department of Civil, Environmental and Natural Resources Engineering, Operation, Maintenance and Acoustics.
    Evaluation of impact sound insulation from 20 Hz2017In: / [ed] Gibbs B., International Institute of Acoustics and Vibration , 2017Conference paper (Refereed)
    Abstract [en]

    In order to reduce costly downtime, adequate condition monitoring of the automatic transmission components in heavy duty construction equipment is necessary. The transmission in such equipment enables to change the gear ratio automatically. Further, the bearings in an automatic transmission provide low friction support to its rotating parts and act as an interface separating stationary from rotating components. Wear or other bearing faults may lead to an increase in energy consumption as well as failure of other related components in the automatic transmission, and thus costly downtime. In this study, different sensor data (particularly vibration) was collected on the automatic transmission during controlled test cycles in an automatic transmission test rig to enable adequate condition monitoring.

    An analysis of the measured vibration data was carried out using signal processing methods. The results indicate that predictive maintenance information related to the automatic transmission bearings may be extracted from vibrations measured on an automatic transmission. This information may be used for early fault detection, thus improving uptime and availability of heavy duty construction equipment.

  • 18. Ljunggren, Fredrik
    et al.
    Wang, Junye
    Luleå tekniska universitet.
    Ågren, Anders
    Luleå University of Technology, Department of Civil, Environmental and Natural Resources Engineering, Operation, Maintenance and Acoustics.
    Human perception thresholds when exposed to vibrations of single and double frequency components2004In: Proceedings - Inter-Noise 2004, the 33rd International Congress and Exposition on Noise Control Engineering: Prague, Czech Republic, August 22 - 25 / [ed] Josef Novák, Prague: International institute of noise control engineering , 2004Conference paper (Refereed)
  • 19. Ljunggren, Fredrik
    et al.
    Wang, Junye
    Luleå tekniska universitet.
    Ågren, Anders
    Luleå University of Technology, Department of Civil, Environmental and Natural Resources Engineering, Operation, Maintenance and Acoustics.
    Human vibration perception from single- and dual-frequency components2007In: Journal of Sound and Vibration, ISSN 0022-460X, E-ISSN 1095-8568, Vol. 300, no 1-2, p. 13-24Article in journal (Refereed)
    Abstract [en]

    This paper covers three different studies with respect to human perception of vertical vibrations. Although the amplitudes and frequencies throughout the experiments are set to match those that might occur in lightweight floor constructions, the results can be seen as general. A motion simulator generates signals from 5 to 31.5 Hz and the test subjects receive the vibrations sitting on a wooden chair. In the first study, the absolute threshold values from sinusoidal signals are determined. The results agree reasonably well with those found from other similar studies. In study number two, threshold values are determined in the presence of an 8 Hz base component. The threshold values were generally found to be higher than those obtained in the first study, except in the case of 10 Hz which due to beating effect gave an even lower threshold level than when the signal was played alone. The third study is about annoyance from dual sinusoidal vibrations, always including a base signal of 8 Hz at fixed amplitude. In similarity with study two, test persons reported to be more annoyed as the second signal component gets close to the base frequency and, naturally, they also got more annoyed as the amplitude increased.

  • 20.
    Ljunggren, Fredrik
    et al.
    Luleå University of Technology, Department of Civil, Environmental and Natural Resources Engineering, Operation, Maintenance and Acoustics.
    Ågren, Anders
    Acoustics in wooden buildings. State of the art 2008: Vinnova project 2007-016532008In: Acoustics in wooden buildings. State of the art 2008, Stockholm: SP Sveriges Tekniska Forskningsinstitut , 2008Chapter in book (Other academic)
  • 21.
    Ljunggren, Fredrik
    et al.
    Luleå University of Technology, Department of Civil, Environmental and Natural Resources Engineering, Operation, Maintenance and Acoustics.
    Ågren, Anders
    Development of a new damper to reduce resonant vibrations in lightweight steel joist floors2002In: Applied Acoustics, ISSN 0003-682X, E-ISSN 1872-910X, Vol. 63, no 11, p. 1267-1280Article in journal (Refereed)
    Abstract [en]

    Floor vibrations annoying to humans often occur in lightweight constructions. A number of methods to solve the problem of resonant vibrations are reported in the literature. Tuned mass damper, semi-active tuned vibration absorber and active control system are all examples of existing methods. A new method has been tested in laboratory environment on a prefabricated floor containing a resilient ceiling with a size up to 6.8×4.8 m2. The method takes advantage of small pieces of visco-elastic material connected between the ceiling joists and the primary beams. A finite element model is used to calculate the correct amount of visco-elastic material. The new damper is especially effective in damping mode shapes where the ceiling oscillates out of phase relative to the floor but shows improvements for other mode shapes as well.

  • 22.
    Ljunggren, Fredrik
    et al.
    Luleå University of Technology, Department of Civil, Environmental and Natural Resources Engineering, Operation, Maintenance and Acoustics.
    Ågren, Anders
    Dynamic and subjective analysis of a lightweight/semi-heavyweight floor in a laboratory2009In: Collected Papers in Building Acoustics: Sound Transmission, Brentwood: Multi-Science Publishing, 2009, p. 79-96Chapter in book (Other academic)
  • 23.
    Ljunggren, Fredrik
    et al.
    Luleå University of Technology, Department of Civil, Environmental and Natural Resources Engineering, Operation, Maintenance and Acoustics.
    Ågren, Anders
    Dynamic and subjective analysis of a lightweight/semi-heavyweight floor in a laboratory2006In: Building Acoustics, ISSN 1351-010X, Vol. 13, no 4, p. 255-272Article in journal (Refereed)
    Abstract [en]

    A lightweight steel framed floor was tested in a laboratory for eight configurations: continuous/lumped main support, support/unsupported free long sides and concrete/plasterboard as top. The dynamic properties were revealed by modal analysis and subjective evaluations in terms of body perception and perception of vibrating articles. The results showed that the tested parameter that affects the floor most was the top layer. The semi-heavy weight floor with concrete layer was in general judged to be of higher acceptance than the lightweight floor having plaster-boards on the top. Additionally, the lightweight floor was used in a series of experiments where the effect of modified support and the effect of adding line loads of various degree of mechanical connection were tested. This part aims to simulate how the dynamics of a floor stepwise might change going from a bare floor to a floor installed inside a real building. The results show that the line load, mass and stiffness influence the floor in terms of changed natural frequencies. Depending on where on the floor the loads are located, different modes were affected and, depending on how the loads were connected to the floor, the gained stiffness varied slightly

  • 24.
    Ljunggren, Fredrik
    et al.
    Luleå University of Technology, Department of Civil, Environmental and Natural Resources Engineering, Operation, Maintenance and Acoustics.
    Ågren, Anders
    Luleå University of Technology, Department of Civil, Environmental and Natural Resources Engineering, Operation, Maintenance and Acoustics.
    Elastic layers to reduce sound transmission in lightweight buildings2013In: Building Acoustics, ISSN 1351-010X, Vol. 20, no 1, p. 25-42Article in journal (Refereed)
    Abstract [en]

    To obtain satisfactory sound insulation is a challenging task when designing lightweight buildings. Poor performance at low frequencies as well as severe flanking transmission has traditionally often been more pronounced compared to heavier constructions. In the present casestudy based paper, various aspects of using elastic layers to improve sound insulation in lightweight buildings are considered.The effect on impact and airborne sound insulation by using two different kinds of vibration insulators between floor plans was examined together with the effect of using glues of various degree of elasticity in the construction. In situ measurements were performed inside a four-storey wooden frame based residential building and statistically significant variations in sound insulation were found.The efficiency of the two vibration insulators was further evaluated by vibration reduction measurements over the junctions. The difference in vibration reduction was found to be nearly constant in the frequency range 50-1000 Hz while the improvement of impact sound insulation increased by frequency.Along term test of elastic glues was also conducted, during three years, for stability over time. The best glues preserved a significantly higher damping ratio over time compared to the main part of the glues.

  • 25. Ljunggren, Fredrik
    et al.
    Ågren, Anders
    Luleå University of Technology, Department of Civil, Environmental and Natural Resources Engineering, Operation, Maintenance and Acoustics.
    How to improve impact sound insulation in a lightweight module based building system2007Conference paper (Refereed)
    Abstract [en]

    This paper covers the initial work in a project where the focus is to improve impact sound insulation for a lightweight module based building system. The size of each module could typically be a small apartment (one room student apartment) or a part of a larger apartment (like two bedrooms or a living room). Modules are prefabricated in a factory, indoors, and are then assembled together at the building yard to form a complete multi-storey building up to fives floors.This building technique often suffers from poor impact sound insulation, especially at low frequencies. A number of parameters that potentially affect the impact sound have undergone experimental testing performed on a setup of two modules, one upper and one lower. Examples of tested parameters: single vs. double layer of floor plaster boards, grey rag boards vs. underlayer foam under the parquet flooring, varying load (weight) on the module and varying kind of vibration insulation in between the modules.

  • 26.
    Ljunggren, Fredrik
    et al.
    Luleå University of Technology, Department of Civil, Environmental and Natural Resources Engineering, Operation, Maintenance and Acoustics.
    Ågren, Anders
    Luleå University of Technology, Department of Civil, Environmental and Natural Resources Engineering, Operation, Maintenance and Acoustics.
    How to match building acoustic measurements with subjective judgments2012In: Inter-Noise 2012, 2012, Vol. 11, p. 8922-8996Conference paper (Other academic)
    Abstract [en]

    The Swedish research program AkuLite deals with various aspects regarding sound and vibration within lightweight buildings. As the popularity of lightweight block of flats increases it has been noticed that standardised (ISO) measurements, like airborne and impact sound insulation, tend to show different correlation with subjective experiences compared with concrete buildings. It is therefore of importance to either develop existing evaluation methods or to find new measurement parameters for better correspondence. In the project, series of sound and vibration measurements are carried out in various types of buildings. The measurements include extended frequency range and various sources as well as increased number of extracted parameters compared to existing standards. In parallel, questionnaires are distributed to the tenants, in the same buildings, where they give answer to questions regarding the experienced sound annoyance in their flat. Statistical analysis of the correlation between the objective measurement parameters and the subjective opinions from the tenants will be carried out.

  • 27. Ljunggren, Fredrik
    et al.
    Ågren, Anders
    Luleå University of Technology, Department of Civil, Environmental and Natural Resources Engineering, Operation, Maintenance and Acoustics.
    Minor construction measures that influence vibrations in lightweight floors2003In: Proceedings of the 10th International Congress on Sound and Vibration (ICSV10): Stockholm, July 7-10, 2003 / [ed] A. Nilsson; H. Bodén, Institute of Acoustics , 2003, p. 4579-4586Conference paper (Refereed)
    Abstract [en]

    The minor construction measures that influence vibration in lightweight floors were presented. A lightweight steel framed floor equipped with a resilient ceiling was used as test object under laboratory conditions. The ceiling joist stiffness was analyzed by a finite element model where both thickness of material and position of the mounting screws were considered. Two different kinds of joists were tested on a floor section. The effect of a visco-elastic material in conjunction with the joists, to increase the damping, were also shown.

  • 28. Ljunggren, Fredrik
    et al.
    Ågren, Anders
    Luleå University of Technology, Department of Civil, Environmental and Natural Resources Engineering, Operation, Maintenance and Acoustics.
    Potential solutions to improved sound performance of volume based lightweight multi-storey timber buildings2011In: Applied Acoustics, ISSN 0003-682X, E-ISSN 1872-910X, Vol. 72, no 4, p. 231-240Article in journal (Refereed)
    Abstract [en]

    Lightweight building systems in general suffer from poor sound insulation, especially in the low frequency region. Since no reliable mathematical models that can predict the impact sound pressure level exists, the lightweight building design is to a high extent based upon previous experience and upon measurements. A special difficulty is related to experimental measurements since the variation among identical units must not be neglected. A modern volume based lightweight wooden buildingn concept has here been tested by numerous well controlled measurements, in laboratory as well as in more field like conditions. The volume construction technique offers new possibilities and challenges to improve sound insulation in light weight timber construction. The main purpose was to investigate how different constructional solutions in the floor, like plaster board, mineral wool, elastic glue, dividing board, floating floor etc., affect the sound insulation. Many of the tested modifications resulted in only marginally changed impact sound pressure level but parameters that substantially can improve the sound insulation were found in using elastic glue to mount the floor boards, to install extra board layers and to use floating floors.

  • 29. Ljunggren, Fredrik
    et al.
    Ågren, Anders
    Luleå University of Technology, Department of Civil, Environmental and Natural Resources Engineering, Operation, Maintenance and Acoustics.
    Using visco-elastic damper to reduce resonant vibrations in a lightweight steel joist floor equipped with resilient ceiling2002In: Proceedings of Inter-Noise 2002, the 2002 International Congress and Exposition on Noise Control Engineering [and] additional proceedings: SQS 2002, Dearborn, Michigan, USA, August 22, 2002 [and] additional information: technical activities of INCE/USA and International INCE, Dearborn, Mich: Institute of noise control engineering , 2002Conference paper (Refereed)
  • 30.
    Ljunggren, Fredrik
    et al.
    Luleå University of Technology, Department of Civil, Environmental and Natural Resources Engineering, Operation, Maintenance and Acoustics.
    Ågren, Anders
    Wang, J.
    Luleå tekniska universitet.
    Knutsson, H.
    Luleå tekniska universitet.
    Reduction of light weight floor vibrations through a visco-elastic damper solution and through addition of building structure elements2002In: 3rd European Congress on Acoustics, 2002Conference paper (Refereed)
  • 31.
    Ljunggren, Fredrik
    et al.
    Luleå University of Technology, Department of Civil, Environmental and Natural Resources Engineering, Operation, Maintenance and Acoustics.
    Öqvist, Rikard
    Luleå University of Technology, Department of Civil, Environmental and Natural Resources Engineering, Operation, Maintenance and Acoustics.
    Simmons, Christian
    Luleå University of Technology.
    An empirical study of the spatial uncertainty of reverberation time measurement below 50 Hz2016In: InterNoise 2016: 45th International Congress and Exposition on Noise Control Engineering: Towards a Quieter Future / [ed] von Estorff O., Kropp W., Schulte-Fortkamp B, German Acoustical Society , 2016, p. 3661-3665Conference paper (Refereed)
    Abstract [en]

    The relevance of performing reverberation time measurements at very low frequencies became an issue in Sweden when the national standard recommended that impact sound insulation should be evaluated from 20 Hz for sound classes above the minimum requirement. Even though the standard states that L'n,T is not to be normalized with respect of reverberation time for frequencies below 50 Hz, it could be argued to include such a correction term to handle any possible variation in the absorption properties of the room. But this can be done only if the reverberation time can be accomplished with reasonable accuracy. The present paper presents an empirical study where reverberation time has been measured from 20 Hz in two different bedrooms with more than 100 microphone positions in each in order to determine the spatial variation. A comparison is made between the uncertainty as a function of frequency and it is indicated that the standard deviation is larger for the lowest frequencies, below 50 Hz, compared to higher. From an engineering point of view, this can be compensated by adding additional positions to the already existing ISO measurement procedure

  • 32.
    Ljunggren, Fredrik
    et al.
    Luleå University of Technology, Department of Civil, Environmental and Natural Resources Engineering, Operation, Maintenance and Acoustics.
    Öqvist, Rikard
    Luleå University of Technology, Department of Civil, Environmental and Natural Resources Engineering, Operation, Maintenance and Acoustics.
    Simmons, Christian
    Luleå University of Technology. Simmons akustik och utveckling, Gothenburg, Sweden.
    Uncertainty of in situ low frequency reverberation time measurements from 20 Hz: An empirical study2016In: Noise Control Engineering Journal, ISSN 0736-2501, E-ISSN 2168-8710, Vol. 64, no 6, p. 706-715Article in journal (Refereed)
    Abstract [en]

    Measuring reverberation time is normally one of the steps within the procedure of determining sound insulation in dwellings where 100 or 50 Hz usually serves as the lower frequency limit. However, even lower frequencies have become a matter of interest as research in the field recently indicated that the range 20-50 Hz seems to be of great importance when it comes to the perception of impact sound in lightweight buildings. A major issue in this context is then whether it is appropriate to measure and evaluate reverberation time at such low frequencies. This paper presents an empirical study of reverberation time measurements made in two rooms using more than 100 microphone positions in each. The measurement uncertainty with respect to microphone position and combinations of positions are compared for the frequency bands from 16 to 1600 Hz. Furthermore, it is analyzed how many microphone positions are needed in order to, with a reasonable probability, end up with an uncertainty in the related standardized impact sound level insulation L′n,T within ±1 dB

  • 33. Mosharrof, Mohammad Sazzad
    et al.
    Brunskog, Jonas
    Acoustic Technology, Department of Electrical Engineering, Technical University of Denmark.
    Ljunggren, Fredrik
    Luleå University of Technology, Department of Civil, Environmental and Natural Resources Engineering, Operation, Maintenance and Acoustics.
    Ågren, Anders
    Luleå University of Technology, Department of Civil, Environmental and Natural Resources Engineering, Operation, Maintenance and Acoustics.
    An improved prediction model for the impact sound level of lightweight floors: Introducing decoupled floor-ceiling and beam-plate moment2011In: Acta Acoustica united with Acustica, ISSN 1610-1928, E-ISSN 1861-9959, Vol. 97, no 2, p. 254-265Article in journal (Refereed)
    Abstract [en]

    To better understand the complex acoustic behaviour of lightweight building structures both experimental and theoretical approaches are necessary. Within the theoretical approach developing theoretical models is of great importance. The aim here is to further develop an existing method to predict the impact sound pressure level in a receiving room for a coupled floor structure where floor and ceiling are rigidly connected by beams. A theoretical model for predicting the impact sound level for a decoupled floor structure, which has no rigid mechanical connections between the floor and the ceiling, is developed. An analytical method has been implemented, where a spatial Fourier transform method as well as the Poisson's sum formula is applied to model transformed plate displacements. Radiated sound power was calculated from these displacements and normalized sound pressure levels were calculated in one-third octave frequency bands. The predicted results from the model are compared with the results from the experiments on the decoupled floor-ceiling construction. The results gave agreements in line with comparisons regarding previous model. The effect of introducing beam-plate moment in the model is studied and is found to be dependent on frequency, showing significant improvement in predicting impact sound level at high frequency region.

  • 34. Mosharrof, Mohammad Sazzad
    et al.
    Ljunggren, Fredrik
    Ågren, Anders
    Luleå University of Technology, Department of Civil, Environmental and Natural Resources Engineering, Operation, Maintenance and Acoustics.
    Brunskog, Jonas
    Prediction model for the impact sound pressure level of decoupled lightweight floors2009In: 38th International Congress and Exposition on Noise Control Engineering 2009: INTER-NOISE 2009 ; Ottawa, Canada, 23 - 26 August 2009 / [ed] J. Stuart Bolton, Red Hook, NY: Curran Associates, Inc., 2009, p. 2038-2046Conference paper (Refereed)
    Abstract [en]

    Prediction of impact sound insulation in timber buildings is difficult since the constructions are complex, non isotropic and show large variances. There are earlier publications on precise models of simplified structures and simplified models of complex structures, where so far, none is considered as an acceptable simplified engineering model tool. The goal of our research is to develop methodology for such a simplified engineering tool. The starting focus is to model impact sound in a simple floor model of two plates that are realistically coupled via beams. The floor structure in Nordic countries is mostly decoupled, meaning there is either no structural connection or an elastic connection between the plates and the beams. In this paper, an improved floor model is proposed where as a first step there is no physical connection between the plates and beams, and where each plate is stiffened by separate beams. Hence the construction becomes more realistic as only coupling between the plates via air trapped inside the cavity is taken into account. Next step will be to introduce resilient coupling between the respective beams. The modelling show promising results with reasonable sound insulation improvements.

  • 35.
    Simmons, Christian
    et al.
    Simmons akustik & utveckling.
    Ljunggren, Fredrik
    Luleå University of Technology, Department of Civil, Environmental and Natural Resources Engineering, Operation, Maintenance and Acoustics.
    Hagberg, Klas
    WSP, Gothenburg.
    Findings from the AkuLite project: New single numbers for impact sound 20-5000 Hz based on field measurements and occupants’ surveys2013In: Internoise 2013: Noise Control for Quality of Life, Innsbruck, 2013, Vol. 3, p. 1882-1889Conference paper (Refereed)
    Abstract [en]

    Impact sounds at very low frequencies as well as floor vibrations may bother occupants in high riseapartment buildings where floors and walls are supported by timber (or steel) frames. Disturbing impactsounds at medium and high frequency may occur in buildings with conrete floors. A weighted singlenumber should preferably handle both types of sounds such that it is neutral with respect to buildingmaterials. This paper presents a brief overview of some main findings of the Swedish ‘AkuLite’ jointresearch project and discuss two single numbers for impact sound evaluated in the frequency range 20-5000Hz as well as a deflection criterion. These single numbers were based on results from field surveys wherethe occupants have rated the performance of their buildings as well as physical measurements in these. In acompanion paper by Ljunggren et al, the airborne and impact sound single numbers are evaluated by meansof correlation analyses. In listening tests by Thorsson, walking impact sounds were recorded on differenttypes of floor and played back to test subjects by means of paired comparisons. Jarnerö made a survey onfloor vibrations. Their results support the hypothesis, that an extension of the frequency range down to 20Hz as well as introducing a stricter deflection criterion could improve the correlation of physical parametersto occupants’ rating of annoyance from impact sounds.

  • 36.
    Simmons, Christian
    et al.
    Simmons akustik & utveckling.
    Ljunggren, Fredrik
    Luleå University of Technology, Department of Civil, Environmental and Natural Resources Engineering, Operation, Maintenance and Acoustics.
    Hagberg, Klas
    WSP, Gothenburg.
    New single numbers for impact sound 20-5000 Hz based on field measurements and occupants’ surveys2013In: Internoise 2013: Noise Control for Quality of Life, 2013Conference paper (Refereed)
    Abstract [en]

    Impact sounds at very low frequencies as well as floor vibrations may bother occupants in high riseapartment buildings where floors and walls are supported by timber (or steel) frames. Disturbing impactsounds at medium and high frequency may occur in buildings with conrete floors. A weighted singlenumber should preferably handle both types of sounds such that it is neutral with respect to buildingmaterials. This paper presents a brief overview of some main findings of the Swedish ‘AkuLite’ jointresearch project and discuss two single numbers for impact sound evaluated in the frequency range 20-5000Hz as well as a deflection criterion. These single numbers were based on results from field surveys wherethe occupants have rated the performance of their buildings as well as physical measurements in these. In acompanion paper by Ljunggren et al, the airborne and impact sound single numbers are evaluated by meansof correlation analyses. In listening tests by Thorsson, walking impact sounds were recorded on differenttypes of floor and played back to test subjects by means of paired comparisons. Jarnerö made a survey onfloor vibrations. Their results support the hypothesis, that an extension of the frequency range down to 20Hz as well as introducing a stricter deflection criterion could improve the correlation of physical parametersto occupants’ rating of annoyance from impact sounds.

  • 37.
    Ågren, Anders
    et al.
    Luleå University of Technology, Department of Civil, Environmental and Natural Resources Engineering, Operation, Maintenance and Acoustics.
    Ljunggren, Fredrik
    Luleå University of Technology, Department of Civil, Environmental and Natural Resources Engineering, Operation, Maintenance and Acoustics.
    In situ measured flanking transmission in light weight timber houses with elastic flanking isolators2013In: InterNoise 2013: Noise control for quality of life, INnsbruck, 2013, Vol. 3, p. 1899-1908, article id 1019Conference paper (Refereed)
    Abstract [en]

    There is a strong trend to industrially produce multi-storey light weight timber based houses. This concept allows the buildings to be manufactured to a more or less prefabricated extent. Most common types are volume/room modules or flat wall and floor modules. When assembling the modules at the building site, elastomer isolators are used in several constructions to reduce flanking transmission. The sound insulation demands in the Nordic countries are relatively high and therefore the flanking transmission must be well controlled, where elastomer isolators are an alternative. Decoupled radiation isolated walls is another. There are though no working studies or mathematical models of the performance of these isolators. They are only treated as simple mass-springs systems that operate vertically, i.e. one degree of freedom. In this paper there is an analysis of experimentally data of the structure borne sound isolating performance of elastomer isolators that are separating an excited floor from receiving walls. The performance dependence of structure type is also presented. An empirically based regression model of the vibration level difference is derived. The model is based on measurements of six elastomer field installations, which are compared to five comparable installations without elastomers. A goal is that the model can be used for input in future SEN prediction models for modeling of sound insulation.

  • 38.
    Ågren, Anders
    et al.
    Luleå University of Technology, Department of Civil, Environmental and Natural Resources Engineering, Operation, Maintenance and Acoustics.
    Ljunggren, Fredrik
    Luleå University of Technology, Department of Civil, Environmental and Natural Resources Engineering, Operation, Maintenance and Acoustics.
    In situ measured flanking transmission in light weight timber houses with elastic flanking isolators: Part II2016In: InterNoise 2016: 45th International Congress and Exposition on Noise Control Engineering: Towards a Quieter Future / [ed] von Estorff O., Kropp W., Schulte-Fortkamp B, German Acoustical Society , 2016, p. 3772-3781Conference paper (Refereed)
    Abstract [en]

    There is a strong trend to industrially produce multi-storey light weight timber based houses. The concept allows the buildings to be manufactured to a more or less prefabricated extent. Most common types are volume/room modules or flat wall and floor modules. When assembling the modules at the building site, elastomer isolators are used in several constructions to reduce flanking transmission. The sound insulation demands in the Nordic countries are relatively high and therefore the flanking transmission must be well controlled, where elastomer isolators are an established alternative. Decoupled shielding wall elements is another. There are though no working studies or mathematical models of the performance of these isolators. They are treated as simple mass-springs systems that operate vertically, i.e. one degree of freedom. In this paper there are analyses of an expanded set of experimental data of the structure borne sound isolating performance of elastomer isolators, which are separating an excited floor from receiving walls. This part II study now includes all in all 9 buildings. The isolation performance dependence on structure type is analyzed. An empirically based regression model of the vibration level difference is derived. The model is based on measurements of 8 elastomer field installations, which are compared to an installation without elastomers. A goal is that the data can be used for input in future SEN prediction models for modeling of the flanking transmission part of sound insulation

  • 39.
    Ågren, Anders
    et al.
    Luleå University of Technology, Department of Civil, Environmental and Natural Resources Engineering, Operation, Maintenance and Acoustics.
    Ljunggren, Fredrik
    Luleå University of Technology, Department of Civil, Environmental and Natural Resources Engineering, Operation, Maintenance and Acoustics.
    Jarnerö, Kirsi
    SP Wood Technology Växjö.
    Bolmsvik, Åsa
    Department of Timber Engineering, Lineaus University.
    Flanking transmission in light weight timber houses with elastic flanking isolators2012In: InterNoise 2012, 2012, Vol. 3, p. 2289-2300Conference paper (Other academic)
    Abstract [en]

    There is a strong trend to industrially produce multi-storey light weight timber based houses. This concept allows the buildings to be manufactured to a more or less prefabricated extent. Most common types are volume/room modules or flat wall and floor modules. When assembling the modules at the building site, elastomer isolators are used in several constructions to reduce flanking transmission. The sound insulation demands in the Nordic countries are relatively high and therefore the flanking transmission must be well controlled, elastomer isolators is one choice. Decoupled radiation isolated walls is another. There are though no working studies or mathematical models of the performance of these isolators. They are only treated as simple mass-springs systems that operate vertically. In this paper there is a first approach of an analysis of the structure borne sound isolating performance of elastomer isolators that are separating floors and walls. The performance dependence of structure type is also presented. An empirically based regression model of the insertion loss is derived. The model will be based on measurements of more than ten field installations. In this paper the first three are presented. A goal is that the model can be used for input in future SEN prediction models for modeling of sound insulation.

  • 40.
    Ågren, Anders
    et al.
    Luleå University of Technology, Department of Civil, Environmental and Natural Resources Engineering, Operation, Maintenance and Acoustics.
    Shi, W.
    Luleå tekniska universitet.
    Ljunggren, Fredrik
    Sound insulation in light weight building structures: A. Development of a full scale test house and a steel beam floor B.Omproved model for impact sound predictions2000In: Proceedings: Inter.Noise 2000 : August 27 - 30, 2000, Nice, France / [ed] Didier Cassereau, Paris: SFA , 2000, p. 348-354Conference paper (Refereed)
  • 41.
    Öqvist, Rikard
    et al.
    Tyréns AB, Umeå, Sweden.
    Ljunggren, Fredrik
    Luleå University of Technology, Department of Civil, Environmental and Natural Resources Engineering, Operation, Maintenance and Acoustics.
    Variations in sound insulation from 20 Hz in lightweight dwellings2018In: Noise Control Engineering Journal, ISSN 0736-2501, E-ISSN 2168-8710, Vol. 66, no 1, p. 56-65Article in journal (Refereed)
    Abstract [en]

    The objective of this study is to quantify the total variations in impact and airborne sound insulation from 20 and 50 Hz, respectively, within a wood-based building system. Field measurements in 70 rooms have been statistically analyzed, in weighted metrics and in third octave bands. Since 1994, the Swedish building code permits wood-based high-rise multifamily dwellings. However, the low frequency sound insulation soon turned out to be insufficient, and complaints were more common in lightweight buildings compared to traditional heavy constructions. Therefore, in 1999, the extended frequency range 50–3150 Hz was introduced in the requirements, an action that mitigated the problem, but only to some extent. Consequently, the lightweight industry often aims one sound class (4 dB) higher than the minimum requirements to obtain satisfactory performance. The Swedish research program Aku20 (2014–2017) showed that the correlation between measured and perceived impact sound insulation in lightweight constructions was significantly improved, when even lower frequencies (20–50 Hz) were included. In this context, the variations of low frequency field measurements and corresponding safety margins need to be investigated.

  • 42.
    Öqvist, Rikard
    et al.
    Tyréns AB, Umeå.
    Ljunggren, Fredrik
    Luleå University of Technology, Department of Civil, Environmental and Natural Resources Engineering, Operation, Maintenance and Acoustics.
    Johnsson, Roger
    Luleå University of Technology, Department of Civil, Environmental and Natural Resources Engineering, Operation, Maintenance and Acoustics.
    Listening test of walking noise from 20 Hz in dwellings2017In: INTER-NOISE 2017: 46th International Congress and Exposition on Noise Control Engineering: Taming Noise and Moving Quiet, Institute of Noise Control Engineering , 2017Conference paper (Refereed)
    Abstract [en]

    Walking noise annoyance from the neighbor above tend to be higher in lightweight than in heavy constructions, even with exactly the same measured impact sound level. The Swedish research program AkuLite indicated that the correlation between measured impact sound insulation and annoyance was significantly improved by extending current ISO evaluation methods from 50 Hz down to 20 Hz. Consequently, there is a need to develop new metrics of impact sound insulation that better correspond to the perceived sound quality. The objective of this study was to verify whether frequencies between 20-50 Hz are important for walking noise annoyance and to evaluate which impact sound level metric that best correlates with walking noise annoyance. The methodology was to evaluate annoyance based on binaural recordings of walking noise in a two-part listening test. The stimuli were reproduced using a combination of headphones and subwoofer. Two living rooms were evaluated, one lightweight wooden construction and one heavy concrete construction. Both rooms achieved similar weighted impact sound level when evaluated from 50 Hz, but the rated annoyance differed significantly. The need to consider frequencies down to 20 Hz in lightweight constructions was verified. The best correlation between measured impact sound level and subjective response was achieved when the evaluation range was extended down to 20 or 25 Hz using a flat frequency weighting factor.

  • 43.
    Öqvist, Rikard
    et al.
    Luleå University of Technology, Department of Civil, Environmental and Natural Resources Engineering, Operation, Maintenance and Acoustics. Tyréns AB.
    Ljunggren, Fredrik
    Luleå University of Technology, Department of Civil, Environmental and Natural Resources Engineering, Operation, Maintenance and Acoustics.
    Johnsson, Roger
    Luleå University of Technology, Department of Civil, Environmental and Natural Resources Engineering, Operation, Maintenance and Acoustics.
    Walking sound annoyance vs. impact sound insulation from 20 Hz2018In: Applied Acoustics, ISSN 0003-682X, E-ISSN 1872-910X, Vol. 135, p. 1-7Article in journal (Refereed)
    Abstract [en]

    There is a need to develop single number quantities (SNQ) of impact sound insulation that correlate better with walking sound annoyance. Previous research has indicated that impact sound insulation should be evaluated from 20 Hz in lightweight constructions, using modified spectrum adaptation terms. The purpose of our study was to verify whether frequencies between 20 and 50 Hz are important for perceived walking sound annoyance and to verify whether the proposed spectrum adaptation terms improve correlation with perceived walking sound annoyance. Binaural recordings of walking sound in one heavy and one lightweight construction were evaluated in a two-part listening test. The need to include frequencies from 20 Hz when evaluating lightweight constructions was verified. Both tested constructions achieved similar performance in terms of LnT,w and LnT,w + CI,50-2500, while a significant mismatch in the rated annoyance was observed. The correlation between SNQ and subjective response was considerably improved, when the impact sound insulation was evaluated from 20 or 25 Hz using a flat frequency-weighting factor.

  • 44.
    Öqvist, Rikard
    et al.
    Luleå University of Technology, Department of Civil, Environmental and Natural Resources Engineering, Operation, Maintenance and Acoustics.
    Ljunggren, Fredrik
    Luleå University of Technology, Department of Civil, Environmental and Natural Resources Engineering, Operation, Maintenance and Acoustics.
    Ågren, Anders
    Luleå University of Technology, Department of Civil, Environmental and Natural Resources Engineering, Operation, Maintenance and Acoustics.
    On the uncertainty of building acoustic measurements: Case study of a cross-laminated timber construction2012In: Applied Acoustics, ISSN 0003-682X, E-ISSN 1872-910X, Vol. 73, no 9, p. 904-912Article in journal (Refereed)
    Abstract [en]

    If variations and uncertainty in building acoustic measurements can be controlled, construction costs can potentially be reduced since the building will not have to be acoustically over-designed. Field measurements of impact and airborne sound insulation were carried out for an industrially prefabricated cross-laminated timber (CLT) system of plate elements. The results from 18 rooms, forming three groups with respect to size, were compared to a similar study dealing with a prefabricated Volume Based Building (VBB) system. Large variations were found at frequencies below 100 Hz which is crucial for the low frequency adaptation terms connected to the weighted sound insulation indices. The measurement uncertainty was investigated by analysing the repeatability, measurement direction and the time dependence of the sound source. The variations due to the measurement procedure were found to be small compared to the total variations. It was also indicated that the variations in sound insulation are smaller with a prefabricated system compared to on-site production, since less work is required at the building site

  • 45. Öqvist, Rikard
    et al.
    Ljunggren, Fredrik
    Ågren, Anders
    Luleå University of Technology, Department of Civil, Environmental and Natural Resources Engineering, Operation, Maintenance and Acoustics.
    The growth of vibro-acoustical properties of volume based timber buildings during the construction phase2010In: Proceedings of 20th International Congress on Acoustics, ICA 2010: 23-27 August 2010, Sydney, Australia, Melbourne: Australian Acoustical Society , 2010, Vol. 4, p. 2700-2707Conference paper (Refereed)
    Abstract [en]

    Variations in sound insulation are a problem for lightweight constructions, since it demands a high safety margin to the legal requirements on acoustical performance, if the variations are large. The building costs can be lowered if these variations can be characterised and identified. This paper describes an investigation of how the vibro-acoustical properties of nominally identical dwellings change during the construction phases. The objective is to find out whether acoustical deviations in the field can be traced to the earlier stages of construction. It also gives an indication of how the variations grow during the process. Throughout the investigation, all measurements were made on the same building elements. The building technique under study is a lightweight timber system consisting of industrially produced prefabricated volumes. Acceleration level measurements have been performed in the factory on building elements at different stages of completion; plates attached to beams, floor with gypsum board covering, the whole volume without floor parquet and the finished volume. An ISO tapping machine was used as excitation source and accelerometers were placed along the edges of the floors and across the surface. Field measurements were performed in the finished building. In addition to the analysis of acceleration level, airborne and impact sound insulation were measured in situ. Acoustical deviations were found for frequencies above 400 Hz, but these could not be traced back to the earlier construction stages.

  • 46. Öqvist, Rikard
    et al.
    Ljunggren, Fredrik
    Luleå University of Technology, Department of Civil, Environmental and Natural Resources Engineering, Operation, Maintenance and Acoustics.
    Ågren, Anders
    Luleå University of Technology, Department of Civil, Environmental and Natural Resources Engineering, Operation, Maintenance and Acoustics.
    Variations in sound insulation in cross laminated timber housing construction2011In: Proceedings of Forum Acusticum: 27 June-01 July, Aalborg, Denmark, European Acoustics Association (EAA), 2011, p. 1649-1654Conference paper (Other academic)
    Abstract [en]

    If variations and uncertainty in building acoustic measurements can be controlled, construction costs can potentially be reduced since the building will not have to be acoustically over-dimensioned. Field measurements of impact and airborne sound insulation were carried out for an industrially prefabricated cross-laminated timber (CLT) system of plate elements. The results from 18 rooms, forming three groups with respect to size, were compared to a similar study dealing with a volume based building system. Large variations were found at frequencies below 100 Hz which is crucial for the low frequency adaptation terms connected to the weighted sound insulation indices. The measurement uncertainty was controlled by analysing the repeatability, measurement direction and the time dependence of the sound source. The variations due to the measurement procedure were found to be small compared to the total variations. It was also indicated that the variations in sound insulation seem to decrease with the amount of workmanship required at the building site

  • 47. Öqvist, Rikard
    et al.
    Ljunggren, Fredrik
    Ågren, Anders
    Luleå University of Technology, Department of Civil, Environmental and Natural Resources Engineering, Operation, Maintenance and Acoustics.
    Variations in sound insulation in multi-storey lightweight timber constructions2009In: 38th International Congress and Exposition on Noise Control Engineering 2009: INTER-NOISE 2009 ; Ottawa, Canada, 23 - 26 August 2009 / [ed] J. Stuart Bolton, Red Hook, NY: Curran Associates, Inc., 2009, p. 315-323Conference paper (Refereed)
    Abstract [en]

    By using industrialized building, pre-installed modules can be delivered to the construction site where they are easily mounted. This method has many advantages compared to on-site manufacturing. In general, the variability of sound insulation is large in lightweight constructions. The reasons behind this variability are not known and therefore the construction is over-dimensioned to make sure the requirements are met. If the causes of this variability can be found and controlled, the production cost will be reduced and the sound quality improved. This is possible, since much of the construction takes place under controlled circumstances. Field measurements of 31 apartments in a four-storey building have been made. Both airborne and impact sound insulation were measured. The apartments on the highest floor achieved significantly better sound insulation. This is an indication that preload is a factor which contributes to high flanking transmission. The structural coupling between modules will therefore be studied in depth. This paper will present the results from the measurements and propose further research.

  • 48. Öqvist, Rikard
    et al.
    Ljunggren, Fredrik
    Ågren, Anders
    Luleå University of Technology, Department of Civil, Environmental and Natural Resources Engineering, Operation, Maintenance and Acoustics.
    Variations in sound insulation in nominally identical prefabricated lightweight timber constructions2010In: Building Acoustics, ISSN 1351-010X, Vol. 17, no 2, p. 91-103Article in journal (Refereed)
    Abstract [en]

    Variations in sound insulation necessitate higher safety margins to the legal requirements, which results in higher production costs. Increased knowledge about variations leads to lowered costs and better sound quality. In-situ measurements of 30 nominally identical apartments of a lightweight timber construction were performed, to assess and quantify the variations in airborne sound reduction and impact sound pressure level. The construction is an industrially prefabricated system of complete volumes. Different sound insulation was found between floor numbers as the apartments on the highest floor achieved significantly better sound insulation. This difference was assumed to be due to the extra weight on lower floors affecting the elastic connections used to structurally connect the apartments. The variation between apartments on the same floor was therefore evaluated using the Root Mean Square Error, resulting in a standard deviation of 0,9 dB and 1,4 dB for the airborne and impact sound insulation, respectively. The measurement variance was subtracted from the total variance. The remaining, unexplainable, variation of 0,8 dB in airborne sound insulation can be attributed to workmanship.

1 - 48 of 48
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