How to change the length of pauses automatically

Hello! I study English and some intervals between phrases in audiocourses are too long and it becomes quite a problem and just a waste of time. Is it possible to “find all silences and reduce their length to 0,5 sec if more” automatically? (Windows XP). Thanks

Try the “Truncate Silence” effect:

I have no “trancate to: () seconds” option.
I couldn’t understand myself because of my poor english I’m sorry.

You appear to be using an obsolete version of Audacity. The current version of Audacity is available here:

I’ve downloaded LADSPA plugins and everything’s OK now! I’m much obliged to you!