I had some trouble getting it up running on windows 11.

I got it working by installing the espeak-ng from the github (1.51 64x.msi version)

And adding this to the python code:

import os

Set the environment variables

os.environ["PHONEMIZER_ESPEAK_LIBRARY"] = r"C:\Program Files\eSpeak NG\libespeak-ng.dll"
os.environ["PHONEMIZER_ESPEAK_PATH"] = r"C:\Program Files\eSpeak NG\espeak-ng.exe"

Verify that they are set

print("PHONEMIZER_ESPEAK_LIBRARY:", os.environ.get("PHONEMIZER_ESPEAK_LIBRARY"))
print("PHONEMIZER_ESPEAK_PATH:", os.environ.get("PHONEMIZER_ESPEAK_PATH"))

Hope it helps if anyone else gets stuck on the same problem.