<p>The main objective of this work was to gain an increasing understanding of the properties of vegetation noise and also to the relative ratios of different natural ambient noises to mask wind turbine sound.</p><p>A discrete vegetation noise model was developed and compared to an earlier model showing improved estimations, especially at frequencies below 0.5 kHz. Field measurements of sound from deleafed trees are compared to a deleafed tree model with satisfactory agreement. A wind turbulence model (Sandia method) was coupled to the discrete model and thereby time series of fluctuating vegetation noise can be computed. Several measurements including higher wind speeds than reported in earlier literature were compared to predictions of fluctuating vegetation noise with good agreement.</p><p>Psycho acoustic tests was performed by 36 subjects to determine the signal-to-noise (S/N) ratios when wind turbine noise is inaudible in three different natural ambient noises. The masking threshold varied between -6.5 dBA and -2.7 dBA for coniferous tree noise and sea wave noise respectively. Further tests revealed that at S/N ratios of +3dBA and above the wind turbine noise was considered as the dominant sound source.</p>
| Identifer | oai:union.ndltd.org:UPSALLA/oai:DiVA.org:kth-4227 |
| Date | January 2006 |
| Creators | Bolin, Karl |
| Publisher | KTH, Aeronautical and Vehicle Engineering, Stockholm : Farkost och flyg |
| Source Sets | DiVA Archive at Upsalla University |
| Language | English |
| Detected Language | English |
| Type | Licentiate thesis, comprehensive summary, text |
| Relation | Trita-AVE, 1651-7660 ; 2006:86 |
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