Clicks appear in encoded file

A lot of clicks appear when I encode this sound track I have.  It starts being
noticeable below quality settings of 5.5, is quite annoying at 5 (which I've
been using as the default setting), and causes me to emit a stream of
four-letter words by the time I lower it to 3.

I'm using the rc3 package in Debian unstable.

A two second sample of the relevant portion is available at the URL above.