Amir has movedJan 25, 2025
So, after JAWS, NVDA is also kissing goodbye to SAPI 4 TTS engines, in 2026.
The support for Microsoft Speech API version 4 synthesizers is planned for removal in NVDA 2026.1. Any remaining users of SAPI4 speech synthesizers are encouraged to choose a more modern speech synthesizer.
https://github.com/nvaccess/nvda/pull/17599
@NVAccess
Fix SAPI 4 driver by SaschaCowley · Pull Request #17599 · nvaccess/nvda

Link to issue number: Fixes #17516 Summary of the issue: After the move to exclusively Windows core audio APIs, the SAPI4 driver stopped working. Description of user facing changes The SAPI4 driver...

GitHub
Show threadgexgd0419Feb 25, 2025
@amir Good news for SAPI 4 users! Now SAPI 4 support is no longer planned for removal in NVDA 2026.1, and all warning messages has been removed. Also, now SAPI 4 voices use WASAPI as well, meaning that features such as audio ducking and leading silence trimming can now work with SAPI 4 voices. Check the newest alpha version alpha-35416, and please report issues you find on GitHub!
Show threadNikola JovićFeb 26, 2025
@gexgd0419 Thanks for your great work. A question though, is it normal that with SAPI4, audio ducking always ducks and never restores the volume of ducked audio, even when it is configured to duck only when speaking? Tested one of the Serbian SAPI4 voices, and that's the behaviour I experience here.
Show threadgexgd0419
@NikJov This is not normal. Audio ducking should either work normally, or not work at all (if the voice does not support custom audio output). But as different SAPI4 engines have different behaviors, I need to get the voice you are using to reproduce and investigate the problem.
Feb 26, 2025 at 1:25amWeb
Show threadNikola JovićFeb 26, 2025
@gexgd0419 I'll see what can be done as it is a commercial voice, but I found out something potentially useful. Pressing CTRL causes audio to return to normal volume after a few seconds, so it is as if the voice is continually speaking even when there's no speech. It's an old synth though so it just being buggy is also a possibility.
Show threadgexgd0419Mar 5, 2025
@NikJov I added verbose logging for SAPI4 in PR #17774. This doesn't fix things, but you can now enable the "synthDriver" debug log category in advanced settings to get a more verbose log file. You can try the snapshot version, then send me the log so that I may be able to understand the problem better.
Show threadNikola JovićMar 5, 2025
@gexgd0419 Thank you, I'll try to get a log as soon as possible, although one user using the same voice as me (Wintalker voice) already reported on GitHub about the experience being significantly worse now, with some audio crackling introduced recently. I observe the same.
Show threadgexgd0419Mar 17, 2025
@NikJov Does the latest snapshot version of PR 17817 make the audio better?
Show threadNikola JovićMar 17, 2025
@gexgd0419 Yes, it's resolved for me now. This is the same synthesizer lpintes on GitHub was reporting about, so I didn't want to make duplicate reports. Thanks.