Active control for adaptive sound zones in passenger train compartments
Independent thesis Advanced level (degree of Master (Two Years)), 20 credits / 30 HE creditsStudent thesis
The acoustics in train compartments is an important part of the comfort when travelling. To improve the acoustics, active noise control (ANC) can be used to create local quiet zones at the passenger ear position. In this thesis the fundamental ANC theory is explained and the possibilities and limitations with the technique are identified. An ANC system which uses the virtual microphone technique is implemented and quiet zones are realized at a chair in a train compartment studio. The performance of the ANC system is evaluated with a Styrofoam head model with built in microphones that is used to produce contour plots of the quiet zone shape and attenuation level. The results show that the 10 dB quiet zone is relatively large covering more than a square decimeter in low frequencies and decreases with frequency. Head movements effects are also evaluated and the results show that the system is very sensitive to head movements, especially in higher frequencies. In order to find an optimal positioning of the system components, several experiments have been made. From these it is concluded that varying noise incidence is problematic to some extent. Ways of handling the problems are presented and if the problems were properly dealt with ANC could be an effective way of reducing noise in passenger train compartments.
Place, publisher, year, edition, pages
2013. , 38 p.
TRITA-AVE, ISSN 1651-7660 ; 2013:36
IdentifiersURN: urn:nbn:se:kth:diva-143502OAI: oai:DiVA.org:kth-143502DiVA: diva2:706756