The thermo-acoustic properties of fibrous material

The compressibility of air inside a loudspeaker enclosure can be increased if the enclosure can be made isothermal. Stuffing fibrous material into an enclosure tends to make it isothermal since the material acts as a heat sink. In order to evaluate the effectiveness of filling material in loudspeaker enclosures, the thermal time response of fibrous materials is calculated. The time response is found to depend on the density of the material and the radius of the fibers. The frequency response of a typical fiberglass material is presented.