Appeal No. 96-0640
Application 08/127,178
volume ratio of spheres to binder material” (Metzger, col. 5,
l. 4-5). Metzger teaches (Metzger, col. 2, l. 22-32):
In accordance with this invention it has been further
found that by providing at least twice the volume of
microspheres to the volume of the resin, improved
attenuation follows. It is theorized that by providing
as large a volume of microspheres as possible that
firstly there is a larger vacuum volume and secondly a
wave traveling through the material will experience an
increased number of transitions between materials of
different index of refraction (glass-resin-vacuum).
Accordingly, we find that persons having ordinary skill
in the art reasonably would have learned from Metzger’s
disclosure that sound transmission is reduced much more by
increasing the number of materials having different indices of
refraction through which the sound must travel, refraction
being a function of the difference in densities of the
materials (Metzger, col. 3, l. 1-6), than by maximizing the
differences in the densities of the refracting materials. Our
finding is consistent with Metzger’s desire that the specific
gravity of the base materials be as small as possible and that
the soundproofing structure most desirably be lightweight
(Metzger, col. 4, l. 18-21).
Thus, while the examiner argues that it is within the
ordinary skill of the artisan optimize amounts of filler
(Ans., pp. 3-4), we find that optimization in line with
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