Appeal No. 98-2325
Application No. 08/546,116
With regard to claim 5, appellants have recognized that a
pore density of 65 pores per linear inch renders the foam
liner effective for noise reduction under high velocity air
conditions (see page 4 of appellants’ specification). Cannan
does not recognize such an effect of the pore density for
polyurethane foam. Instead, Cannan teaches an exhaust air
muffler in which the pore densities of multiple polyurethane
foam layers in an air filter progressively increase from the
inlet end of the filter to the outlet end of filter. In
Cannan’s preferred embodiment, an intermediate layer is
provided with a pore density of 65 pore per linear inch.
However, we agree with appellants that the arbitrary selection
of this intermediate pore density for modifying Sakaki’s
tubular sound-attenuating liner is based on hindsight
knowledge of appellants’ teachings. Hindsight analysis,
however, is clearly improper. In re Deminski, 796 F.2d 436,
443, 230 USPQ 313, 316 (Fed. Cir. 1986). Accordingly, we must
also reverse the § 103 rejection of claim 5.
The examiner’s decision rejecting the appealed claims is
affirmed with respect to claims 1 through 4 and 7, but is
reversed with respect to claims 5 and 6.
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