Arbetet inleds med grunläggande teori för byggnadsakustik. En litteraturstudie genomförs för att ta fram förbättringsalternativ för ett antal konstruktionsdelar för två valda mätobjekt. Efter utförd fältmätning beräknas sammansatt reduktionstal av skiljevägg utifrån uppmätta och utgivna värden. En jämförelse görs och förbättringsalternativen fastställs. Analys av resultat visar dels att odämpade luftdon gör stor negativ verkan på ljudreduktionen för den sammansatta fasadväggen. För lägenhetsavskiljande vägg visar sig resonans uppkomma vid ”fel” uppbyggnad av väggkonstruktionen. / The thesis begins with basic theory of building acoustics. A literature study is made to develop improvement options for a number of building components of the two selected measurement objects. After completion of field measurement, a composite reduction index is calculated for measured and published values. A comparison is made and improvement options are set. Analysis of the results shows that undamped air-vents makes a big negative impact on the noise reduction of the composite facade wall. For apartment separation wall it turns out that resonance occur with a "wrong" wall construction.

Today's urban centers become denser, which contributes to higher demands on sound and noise. It is therefore highly relevant to build homes with good sound environment while maintaining living space. This thesis aimed to reduce the current concrete walls and see how the mass law affects the reduction index value and flanking transmissions. Handmade calculations were calculated according to the Swedish standard SS-EN 21354-1, where only air sound was calculated. Calculations we­­­re performed on wall elements with different weights and thicknesses, and compared with results from Bastian. In Bastian calculations of flanking transmissions were also made, this was made to see the impact of the flanking transmission when changing the mass per unit area. Mass law's impact was examined by flanking transmission and the result shows that they are not affected as long as the ratio between the thickness and the density remains the same. A questionnaire survey was conducted to determine the actual sound experience; this questionnaire was conducted on three concrete buildings in Växjö. Results from hand calculations, Bastian and the questionnaire were analyzed and joined. The mass law affects flanking transmissions very little and therefore a conclusion is drawn that more action is needed and not only improvement of individual elements and how they are connected. Results indicate that today's apartment partitions do well for airborne sound between rooms. In the future this could lead to selection of thinner walls. / Dagens stadskärnor blir tätare och detta bidrar till att högre krav ställs på ljud och buller. Det är därför högaktuellt att bygga bostäder med god ljudmiljö och maximal boyta.  Examensarbetets syfte var att minska dagens lägenhetsavskiljande betongväggar och se hur masslagen påverkar reduktionstalet samt flanktransmissionen. Handberäkningarna är utförda enligt svensk standard SS-EN 21354-1 där enbart luftljud beräknades. Samtliga beräkningar utfördes på väggelement med olika ytvikter och tjocklekar och jämfördes senare med resultat från Bastian. I Bastian beräknades även flanktransmissioner, detta för att se flanktransmissionens inverkan vid ändring av ytvikt. Masslagens inverkan granskades och resultatet visar att flanktransmissionen ej påverkas så länge förhållandet mellan tjockleken och densiteten förblir densamma. En enkätsundersökning utfördes för att bestämma den verkliga ljudupplevelsen, denna undersökning utfördes på tre betonghus i Växjö. Resultat från handberäkningar, Bastian samt enkäten analyserades och sammanställdes. Då masslagen inverkar på flanktransmissionen kan en slutsats dras att det behövs fler åtgärder än enbart förbättring av enskilda element samt hur dessa kopplas ihop. De sammanfogade resultaten pekar på att dagens lägenhetsavskiljande väggar klarar sig bra för luftburet ljud mellan olika lägenheter. Det skulle i framtiden kunna innebära att tunnare väggar väljs, med ökad densitet och bibehållen ljudklass.

A survey is conducted to link sound reduction index with human experiences, the survey shows that the majority of residents value silence in their homes. About one in five residents hear that sound enters their home via the fresh air vents and is willing to pay for a soundproof fresh air vents. The results of the calculations indicate that the reduction index for the measurement object is 29 dB which means that the reduction rate will be 36.6 dB after installation of soundproofed fresh air vent. When switching to a soundproof air vent, an increase of 7,6 dB in sound reduction index is achieved. By providing more information to customers about different air vents with regard to acoustics, knowledge of the subject increases and they can actively take a stand to improve their quality of accommodation. / En enkätundersökning genomförs för att koppla teoretiska värden på reduktionstal till mänskliga upplevelser. Undersökningen visar att majoriteten av de boende värdesätter tystnad i sin bostad. Cirka en av fem boende hör att ljud kommer in i bostaden via friskluftsventilen och är villiga att betala för en ljudisolerad friskluftsventil. Resultatet för samtliga beräkningar visar att det sammansatta reduktionstalet för väggkonstruktionen är 29 dB. Vid byte till en ljudisolerad friskluftsventil ökar reduktionstalet med 7,6 dB vilket innebär att det sammansatta reduktionstalet blir 36,6 dB efter installation av ljudisolerad friskluftventil. Genom att ge mer information till kunderna om olika friskluftsventiler med hänsyn till akustik ökar kunskapen kring ämnet och de kan aktivt ta ställning till att förbättra sin boendekvalité.

Rapidly growing cities require that new residential buildings be created at a matching pace. Moreover, ambitious environmental goals not only call for these buildings to be constructed swiftly, but also in a sustainable manner. Cross-laminated wood, abbreviated CLT, may partly offer a solution to these challenges. During a period when wood was prohibited to serve as a framework material in buildings higher than two stories, the research examining wood as a building material suffered a setback. While the interest in wooden buildings has increased in recent years, there are still uncertainties regarding several of the material’s properties, such as its acoustics. Being able to predict whether a structure will meet the desired acoustic requirements, is vital to contractors and clients in the building industry, as later reconstructions often result in considerable added costs and delays. Thus, tools that help predict acoustic properties are in high demand and may help wood become a more attractive choice of building material. Aiming at decreasing the total thickness of a double-wall without compromising its sound insulation ability, an experiment examining the effects of perforation of a CLT panel and its impact on the sound reduction index (SRI), was conducted. Results indicated that it may be possible to decrease the total thickness of a double wall by perforating the panel, while maintaining and in some cases, increasing the SRI. This study is based on an analytical calculation model which predicts the sound insulation properties of single- and double walls, measured in SRI [dB]. The original model was produced by Sharp and later modified by Ljunggren to obtain a better match for CLT panels. The sample data, provided by the company Martinsons AB, consisted of 32 unique double-wall configurations of which the SRI was modelled. As the original model only applied to configurations assuming total insulation of the cavity, an extension was calculated to apply to configurations comprising no or partial insulation. To validate the model, results were then compared to available data from onsite measurements provided by Tyréns, as well as calculations by Ljunggren. As comparable data is limited and most modelled configurations had no corresponding onsite measured SRI, the results of this study may serve as an indication of what sound insulation quality to expect for those configurations. The predicted SRI for which a corresponding measured SRI did exist, showed good agreement, with deviations of 1-2 dB. Compared to measurements conducted by Tyréns, the modelled SRI were approximately 3-6 dB higher. Measured SRI are under the influence of flanking transmission which often results in it being the lower value, when compared to modelled SRI. However, the relative difference between the two values can still serve as a useful tool. To strengthen these findings and confirm the validity of the model, further research examining a wider range of measurements and comparisons with modelled results should be conducted. / Träcentrum Norr

Projektets syfte har varit att undersöka hur en skiljekonstruktions luftljudsisolering påverkas av att isoleringsmaterialet läggs inuti en papperskudde, samt om luftljudsisoleringen influeras av att pappret är perforerat med 20% perforeringsgrad. Projektet genomfördes genom att konstruera tre olika innerväggar med olika isolering; stenull i operforerade påsar, stenull i perforerade påsar och stenull ”fritt”. Det byggdes en 1,8 x 1 m2 enkel-regelvägg mellan ett ekofritt rum och ett efterklangsrum i Marcus Wallenberg-laboratoriet på KTH. Samtliga väggkonstruktioner hade kantprofiler av stål, stålreglar samt dubbla skivor gips. Mätningarna utfördes i enlighet med ISO 15186–1. Det placerades en rundstrålande högtalare i efterklangsrummet som skapade ett diffust ljudfält med rosa brus och där mättes ljudtrycksnivån. I det ekofria rummet mättes ljudintensitetsnivån genom att väggen skannades med en intensitetsprob. Mätningarna utfördes i ⅓-oktavbandsfilter mellan 50 och 5000 Hz. Reduktionstalet som funktion av frekvens beräknades för varje isolering såväl som det vägda reduktionstalet. Mätningarna resulterade i att väggen med stenull utan påse hade vägt reduktionstal R_w = 49 dB och de båda väggarna med stenull omsluten av påsar hade R_w = 48 dB. Skillnaden i ljudreduktion skiljde sig mest för de låga frekvenserna och stenullen utan påse hade nämnvärt högre reduktionstal för 100 och 125 Hz. För frekvenser över dessa var reduktionstalet mycket likt för samtliga väggkonstruktioner. Väggen med stenull i perforerade påsar hade något bättre ljudreduktion än de två andra väggarna vid 800 Hz samt frekvenser över 2000 Hz.

<p>This report is written on commission by WSP Acoustics. The report studies the outdoor sound levels on school yards in Stockholm. The questions given by the company to be answered was what are the actual sound levels at diffrent school yards with low traffic noise and how can you construct a facade element that reduces the sound level from the outside and meet the indoor requirements. Mesurements for four hours was done at eight schools set north and south of the city centre. The measurement period included one school break and one lunch break. The results of the measurements were that the equivalent and maximum sound level had small variations between the schools with some exceptions.The equivalent sound level was Leq 58-62 dB(A) and this shows a small variation. The school with the highest equivalent sound level of 67 dB was Maria skolan. This high level can be explained by more children on the school yard together at the same time etc. The maximum sound level was 85-89 dB(A), this if the level for Sofia skolan 82 dB was ignored. The level 85-89 dB(A) also shows a small variation. Calculations of the sound reduction index (R'w) for facade elements were also carried out for all the schools. The resulting sound reduction index for the whole facade was 34-41 dB. After assuming a 200 mm thick concrete facade for Sjöstadsskolan another calculation of building elements gives that the window have to reduce R'w 32 dB to meet the indoor requirements. In the future WSP Acoustics will use this report to choose building elements such as windows when building or rebuilding schools. It can also be used if any of the eight schools in this report needs a window changed to improve the acoustics.</p>

This report is written on commission by WSP Acoustics. The report studies the outdoor sound levels on school yards in Stockholm. The questions given by the company to be answered was what are the actual sound levels at diffrent school yards with low traffic noise and how can you construct a facade element that reduces the sound level from the outside and meet the indoor requirements. Mesurements for four hours was done at eight schools set north and south of the city centre. The measurement period included one school break and one lunch break. The results of the measurements were that the equivalent and maximum sound level had small variations between the schools with some exceptions.The equivalent sound level was Leq 58-62 dB(A) and this shows a small variation. The school with the highest equivalent sound level of 67 dB was Maria skolan. This high level can be explained by more children on the school yard together at the same time etc. The maximum sound level was 85-89 dB(A), this if the level for Sofia skolan 82 dB was ignored. The level 85-89 dB(A) also shows a small variation. Calculations of the sound reduction index (R'w) for facade elements were also carried out for all the schools. The resulting sound reduction index for the whole facade was 34-41 dB. After assuming a 200 mm thick concrete facade for Sjöstadsskolan another calculation of building elements gives that the window have to reduce R'w 32 dB to meet the indoor requirements. In the future WSP Acoustics will use this report to choose building elements such as windows when building or rebuilding schools. It can also be used if any of the eight schools in this report needs a window changed to improve the acoustics.