Steps to reproduce:

1. Install SAPI 4 along with a synthesizer. Instructions are available in SAPI4 crashes in alpha-21882,528d5708 #12152.
2. Go to the voice settings, and try to adjust a parameter like rate, pitch, volume, etc.

Actual behavior:

Adjusting rate, pitch and volume doesn't work.

Expected behavior:

Adjusting speech rate, pitch and volume should work.

NVDA logs, crash dumps and other attachments:

System configuration

NVDA installed/portable/running from source:

Installed.

NVDA version:

alpha-29490,2adb77cb.

Windows version:

Windows 11, Version 23H2 (OS Build 25951.1010).

Name and version of other software in use when reproducing the issue:

SAPI 4, American English TruVoice, however this doesn't seem to be specific to any particular synthesizer.

Other information about your system:

N/A.

Other questions

Does the issue still occur after restarting your computer?

Yes.

Have you tried any other versions of NVDA? If so, please report their behaviors.

Yes, 2023.3beta4 works normally.

If NVDA add-ons are disabled, is your problem still occurring?

Yes.

Does the issue still occur after you run the COM Registration Fixing Tool in NVDA's tools menu?

Yes.