| 摘要 |
The known membranes consist of pasteboard or of plastic. These can be manufactured inexpensively and have high internal damping but tend to troublesome partial vibrations in the audible range. Membranes made of metal are expensive; because of their high strength the partial vibrations are admittedly higher but because of the lower internal damping of the metal they are very obtrusive. The proposed membrane (1) consists of corundum which is formed of pure aluminium, which has been brought to the desired shape, by anodic oxidation and subsequent firing at temperatures above 600 DEG C. The method of manufacture of the membrane consisting of corundum is simple and inexpensive and the product is superior to the known membranes in respect of its acoustic properties (partial vibrations, distortion, pulse characteristics). <IMAGE>
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