<p>Today, a high noise level is considered a problem in many working environments. The main reason is that it contributes to stress and fatigue. Traditional methods using passive noise control is only practicable for high frequencies. As a complement to passive noise control, active noise control (ANC) can be used to reduce low frequency noise. The main idea of ANC is to use destructive interference of waves to cancel disturbing noises.</p><p>The purpose of this thesis is to design and implement an ANC system in the driver's cabin of a Valmet 890 forest</p><p>machine. The engine boom is one of the most disturbing noises and therefore the main subjective for the ANC system to suppress.</p><p>The ANC system is implemented on a Texas Instrument DSP development starter kit. Different FxLMS algorithms are evaluated with feedback and feedforward configurations.</p><p>The results indicate that an ANC system significantly reduces the sound pressure level (SPL) in the cabin. Best performance of the evaluated systems is achieved for the feedforward FxLMS system. For a commonly used engine speed of 1500 rpm, the SPL is reduced with 17 dB. The results show fast enough convergence and global suppression of low frequency noise.</p>

Today, a high noise level is considered a problem in many working environments. The main reason is that it contributes to stress and fatigue. Traditional methods using passive noise control is only practicable for high frequencies. As a complement to passive noise control, active noise control (ANC) can be used to reduce low frequency noise. The main idea of ANC is to use destructive interference of waves to cancel disturbing noises. The purpose of this thesis is to design and implement an ANC system in the driver's cabin of a Valmet 890 forest machine. The engine boom is one of the most disturbing noises and therefore the main subjective for the ANC system to suppress. The ANC system is implemented on a Texas Instrument DSP development starter kit. Different FxLMS algorithms are evaluated with feedback and feedforward configurations. The results indicate that an ANC system significantly reduces the sound pressure level (SPL) in the cabin. Best performance of the evaluated systems is achieved for the feedforward FxLMS system. For a commonly used engine speed of 1500 rpm, the SPL is reduced with 17 dB. The results show fast enough convergence and global suppression of low frequency noise.

The purpose of this degree project is to investigate noise problems for residential areas close to roads with very intense traffic. The area Lilla Essingen in Stockholm has been investigated and most focus is on noise measurements outdoors and different measures for noise reduction in the area. Sound measurements are the basis for this work, but calculations have been made to obtain the 24-hour equivalent sound level and maximum sound level for the different measurement points. Interviews are also an important part of this work, where the sales market for apartments located closest to the road is discussed with various brokers from different companies in the area. Furthermore, the harmful health effects that are obtained due to high noise levels, various measures for reducing noise impact and the different measured values ​​at different times during the day are discussed. The own measured and recalculated 24-hour equivalent noise levels from Lilla Essingen are compared with guideline values from both WHO and Stockholm City in order to better understand the importance of the actual noise within this residential area. Sleep disorders, reduced concentration, stress and hearing damage are the most common effects caused by noise and research has shown that noise also has a connection with cardiovascular diseases. Children are most affected by noise; it can affect their learning development and lead to less concentration compared to the other children who are not exposed to equally high sound levels. The own measurement values ​​have shown that sound levels differ during different times of the day and with different distances from the road. The sound is at its highest in the morning where traffic flow is high, but according to the measurements it has shown that the sound levels are always high next to the road even during the evening / night.   Keywords: Noise, noise impact, motorway, guide values, equivalent sound level, maximum sound level, noise reduction, traffic, quiet side / inte

De flesta av Sveriges kommuner har ett mål där de strävar efter att bygga ett hållbart samhälle, vilket innebär att man utnyttjar den befintliga infrastrukturen. Målet med detta är att dra nytta av de obebyggda områdena i stadsbilden genom att bygga nytt. Eftersom de tysta sidorna av byggnaderna ska ligga på en ljudnivå under 45 dB(A) har det här examensarbetet behandlat de möjliga lösningar som kan tillämpas vid bullerdämpning. En platsinventering har utförts där de olika förutsättningarna har studerats, och där resultaten av studierna har granskats med syfte till att planera en vision. Nyckelord: Bullerdämpning, bostadsutformning, platsinventering / Most Swedish municipalities have a goal which they strive to build a sustainable society, which involves the use of the infrastructure. The aim of this is to take advantage of the undeveloped areas of the urban landscape by building new buildings. Since the quiet sides of the buildings shall be at a noise level below 45dB(A), this diploma work addressed the possible solutions that can be applied in noise attenuation. A site survey has been performed there the different conditions have been studied, where the results of the studies have been reviewed in order to plan a vision. Keywords : Noise attenuation, residential design, site survey

Uppsatsen behandlar bullerdämpning vid kap på ProfilGruppen Extrusions AB i Åseda. Problemen med ljudnivån beror bland annat på stomljudet som alstras av kapen i de långa profilerna. För att sänka ljudnivån har fastklampningskonstruktioner tagits fram som dämpar stomljudet och förslag på vidare åtgärder rapporterats. Försök och jämförande mätningar av ljudnivån har utförts för att få ett bra underlag att utvärdera. Resultaten av försöken med viskoelastisk plast som dämpelement visar en viss dämpning. Dämpningen kan med all sannolikhet bli större med användning av tjockare dämpelement. / This project is about noise reduction of a cross cut saw at ProfilGruppen Extrusions AB, Åseda. The problems with the sound level depend on the structure-borne sound that generates in the long profiles. To lower the sound level have press clamp constructions been developed which reduce and further attends have been suggested. Attempts and comperative measurings of the sound level have been evaluated. The results of the comperative measurings with viscoelastic plastic as damping element display certain damping. The damping can in all probability become larger using a thicker damping element.

<p>Uppsatsen behandlar bullerdämpning vid kap på ProfilGruppen Extrusions AB i Åseda. Problemen med ljudnivån beror bland annat på stomljudet som alstras av kapen i de långa profilerna. För att sänka ljudnivån har fastklampningskonstruktioner tagits fram som dämpar stomljudet och förslag på vidare åtgärder rapporterats.</p><p>Försök och jämförande mätningar av ljudnivån har utförts för att få ett bra underlag att utvärdera. Resultaten av försöken med viskoelastisk plast som dämpelement visar en viss dämpning. Dämpningen kan med all sannolikhet bli större med användning av tjockare dämpelement.</p> / <p>This project is about noise reduction of a cross cut saw at ProfilGruppen Extrusions AB, Åseda. The problems with the sound level depend on the structure-borne sound that generates in the long profiles. To lower the sound level have press clamp constructions been developed which reduce and further attends have been suggested.</p><p>Attempts and comperative measurings of the sound level have been evaluated. The results of the comperative measurings with viscoelastic plastic as damping element display certain damping. The damping can in all probability become larger using a thicker damping element.</p>