Checking noweb documents

I'm using Sweave, which allows me to combine R language code and TeX 
commands in the same file. It uses Noweb format 
<http://www.eecs.harvard.edu/~nr/noweb/>, which means that regions 
beginning with \n<<>>= and ending with \@ are processed by R rather than 
TeX. I would prefer not to have these spell-checked in aspell. Is there 
an easier way to do this than writing a new filter? I know I can act on 
the noweb-produced TeX code, but then corrections are not propagated 
back to the original file.