I have strange feeling that Perl scripts are somehow in different environment when run from Asterisk that plain run.

Yes, that's usually the case. When you're testing your scripts from the command line, they are running as you and have the same privileges as your login shell. However, when run by Asterisk, which is often installed under its own account, they are run as the Asterisk user and with its privileges.

For this reason, it's a good idea to double-check any files you need to access or programs you need to run to make sure that their permissions allow access by Asterisk's account. In particular, check out the permissions of files and directories in Festival's voices/us/cmu_us_slt_arctic_hts/ directory.

Per your other question, no, I'm not using the most recent Asterisk and Festival releases. I'm using the stock Fedora Core 1 Festival and a development version of Asterisk that I built about six months ago.

Cheers,
Tom