hi.
do you use espeak bundled with nvda or
do you use espeak sapi5?
if you use espeak of sapi5, it depend on the valume of your choice in
control panel, valume control.
if you use espeak which is installed by default with nvda, i did not
try other synthesizer,
but for me the valume is loud and i select 60 or 70 for its valume.
also, it depend on the voice that you selected.
which variant are you using?

--
By God,
were I given all the seven heavens
with all they contain
in order that
I may disobey God
by depriving an ant
from the husk of a grain of barley,
I would not do it.
imam ali