<p>Validerat; 20120619 (anonymous)</p>

This qualitative study has evolved from an ambition to find methods of increasing the possibilities of creating a stronger dialectics between planned music activities and spontaneous sound creating actions. The aim of this study is thus to describe and analyse children´s spontaneous sound creating actions in unplanned activities as a base for future practical didactic procedures in preschools.The concept of music is expanded to include actions in order to make sound and actions that create sounds and the children´s actions are described and analysed through different subjects´ perspectives by means of a posthumanist intra-active perspective. The importance of materiality as well as the context which constitutes children´s everyday life in preschool is shown through the analysis. The children´s sound creating actions are closely related to continuous processes of becomings in which children, materiality, and also the researcher become different in themselves through intra-action. The materiality, the rooms, the size of the group of children and time can be identified as performative agents that enable several potential outcomes and a variety of contents in children´s spontaneous sound creating actions. The study also shows how the children mainly explore the basic music element timbre. This opens discussions regarding didactic implications and new approaches towards the practical staging of music activities in preschool.

Noise generation from underwater activities propagates into the marine environment.For marine vessels the propulsion system generates the most noise during itsoperations. Naval vessels that want to operate without being detected want to controlthe sound generating properties of the vessel. To control the sound generatingproperties this project has been looking into the existing propeller of the submergedcraft Carrier Seal that is produced by James Fisher Defense. Then a new and bespokenpropeller has been developed with theories applied to minimize its noise generatingproperties. The properties of the propeller that have been altered is the number ofblades, blade area ratio, pitch and skew angle. These properties have been alteredwith aid of the open-source software for Matlab named Openprop. From the finalpropeller design a prototype was later produced, tested and compared to the existingpropeller of the Seal Carrier. To test and compare these two propellers a test procedurewith inspiration from NATO and the Swedish Defense and Research Agency (FOI) wasdeveloped. The results from the comparison show that the sound pressure level fromthe propeller spectrum could be lowered with 3 dB re 1 μP a for the vessels design speedand several blade tones could be eliminated entirely. Simultaneously the efficiency ofthe vessel is increased throughout its speed range.In conclusions the recommendation to JFD is to change their existing propeller tothis bespoken propeller as it has proven itself to better in every way during thesetrials. / Ljud som genererats under vatten sprider sig långt från källan där de uppstått. Frånmarina fartyg är det framdrivningssystemet som står för majoriteten av det genereradeljudet. För militära fartyg som inte vill upptäckas är det av yttersta vikt att minimeraljuden som genereras ombord. För att kontrollera detta har det här projektet riktatin sig på fartyget Carrier Seal som tillverkas utav James Fisher Defense (JFD) ochdess propeller. Den existerande propellern har analyserats och därefter har en nyoch förbättrad propeller utvecklats. Utvecklingen har gjorts genom att tillämpatillgängliga teorier som gått ut på att minska propellerns ljudskapande egenskaper.Propelleregenskaperna som har undersökts är antalet blad som propellern har, dessbladtäckningsgrad, stigning och skevningsvinkel. Dessa egenskaper har varierats medhjälp av mjukvaran Openprop som körs i Matlab för att hitta en kombination somgenererar mindre ljud än sin föregångare. Därefter har en prototyp tillverkats ochtestats för att sedan jämföras med den existerande propellern. Testproceduren somgenomförts har tagits fram med inspiration från liknande procedurer som genomförtsav NATO och FOI. Resultatet från jämförelsen visar att ljudtrycksnivån från propellernhar kunnat minskats med 3 dB re 1 μP a för hela propellerspektrumet vid farkostensmarschfart och flertalet bladtoner kunde elimineras helt och hållet. Samtidigt someffektiviten kunnat förbättras över hela fartområdet.Slutsatsen som kan dras av arbetet är att JFD rekommenderas att byta deras nuvarandepropeller till den förbättrade propellern eftersom den har visat sig avsevärt mycketbättre under dessa tester.