| 摘要 |
An improved acoustic impedance for a direct radiating dynamic loudspeaker having a natural Q greater than about 1.2, is substantially planar and is positioned in front of and covers the projected frontal radiation area of the diaphragm or cone of the loudspeaker. The acoustic impedance element is supported about its periphery and comprises a fibrous felt material having an air flow resistance in the range of about 50-100 cu. ft. per min. at 0.5 p.s.i. pressure drop, a density in the range of about 6-12 oz. per sq. yd. and a thickness in the range of 0.03-0.09 in. The acoustic impedance element is an air permeable continuous sheet and is comprised substantially entirely of fibers of synthetic materials, such as, for example, polyester, which are relatively impervious to moisture. The Q of the speaker including the damping element is in the range of about 0.75-1.0.
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