For GD, you can download Actual English Voice Packages from Lingoes Official Website. All are in MP3 formats. No more worries for ________.dsl.files.zip for Sounds. These are actual human voices recorded by native speakers of English (British and American), not Text To Speech Engines (TTE) which aren't reliable.
from here,
http://www.lingoes.net/en/translator/speech.htm
Lingoes Basic English Voice Package (10,386 words - 24.1 MB)
Longman Modern English 2005 Updated American (A-Z) (40,339 words - 99 MB)
Longman Modern English 2005 Updated British (A-Z) (43,913 words - 130 MB)
Webster Voice Package (A-Z) (141,728 words - 372 MB)
To activate sounds in GD

FYI
The Link for Webster Voice Package is dead but it's googlable. Enjoy.
Kind Regards,
LYNN