The default value of the "fragment" parameter in osssink is 6.  This means that
the fragment size is 2^6 = 64.  On two of my machines, whenever there is a
moderate amount of I/O activity, osssink produces lots of static in addition to
the proper output.  Changing the "fragment" value to 8 (a fragment size of 256
bytes) solves the problem.

According to the 4front documentation for OSS at
http://www.4front-tech.com/pguide/audio2.html:

"With relatively short fragments this may cause whining sound which is very
difficult to identify. Using fragment sizes shorter than 256 bytes is not
recommended as the default mode of application. Short fragments should only be
used when explicitly requested by user."

So I would suggest changing the default value of "fragment" from 6 to 8.