Some I hear easily, some I have to crank up the volume to hear.
E.g. [link|http://www.wikiupload.com/file_store/upload_1/5970476574478882200090.mp3|This one] I hear fine.
[link|http://graphics.nytimes.com/packages/audio/nyregion/20060610_RINGTONE.mp3|This one] I have to turn up the volume to hear easily.
YMMV.
Cheers,
Scott.
(Who hears lots of clicking when playing them on his PC, but doesn't hear clicking when they're played on a Mac.)