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Title Absorption in Loudspeaker Cabinets
Author Olesen, Tobias Schmidt
Supervisor Jacobsen, Finn (Acoustic Technology, Department of Electrical Engineering, Technical University of Denmark, DTU, DK-2800 Kgs. Lyngby, Denmark)
Agerkvist, Finn T. (Acoustic Technology, Department of Electrical Engineering, Technical University of Denmark, DTU, DK-2800 Kgs. Lyngby, Denmark)
Institution Technical University of Denmark, DTU, DK-2800 Kgs. Lyngby, Denmark
Thesis level Bachelor thesis
Year 2008
Abstract The effect of filling a loudspeaker enclosure with porous material is modeled as a transition in the propagation of sound from an adiabatic process to an isothermal process. The result is a lowering of the resonance frequency of the loudspeaker system. This is due to a decrease in the sound velocity causing the acoustic volume to increase and compliance to increase. The frequency range in which isothermal conditions can be assumed is examined and analytical expressions describing the effect of the porous materials on the loud-speaker system is derived. The theory is then compared to measurements of the acoustic compliance of a loudspeaker enclosure filled with porous material and the speed of sound through porous material. Four different kinds of porous materials are used as ling at variating densities. This gives different increases in the compliance due to differences in the proper- ties of the materials. This difference is discussed and the best filling material is determined.
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Admin Creation date: 2009-03-26    Update date: 2009-08-07    Source: dtu    ID: 240726    Original MXD