Random Letters Appearing in Microsoft Word When SAPI Voice Adapter Is Installed

[frameli]

Description: When the SAPI voice adapter is installed, random letters appear in Microsoft Word documents upon opening and reading them with a screen reader, even without making any edits.

Steps to Reproduce:

1. Install the SAPI voice adapter.
2. Open a local Microsoft Word document.
3. Without making any edits, try reading the document with a screen reader (test with NVDA, which is free).
4. Observe whether random letters appear.
5. Close the document and reopen it—letters may appear in different places.
6. Repeat the same test with a document stored on OneDrive.

Example of the Issue (Observed in a Real Case):

Original Document Text:

"The intent of both Pythagoras and his Egyptian and Babylonian predecessors was actually to gain an understanding of the surrounding world and find the most efficient way to interact with it, and their exceptional discoveries such as irrational numbers or fractions are therefore ascribable to the solution of everyday issues, such as the calculation of the salary due to the workers employed in the construction of pyramids or ziggurats."

After Opening and Reading with a Screen Reader:

"bbbbbbbbbbbbbbbbbbbbbbbbThe intent of both Pythagoras and his Egyptian and Babylonian predecessors was actually to gain an understanding of the surrounding world and find the most efficient way to interact with it, and their exceptional discoveries such as irrational numbers or fractions are therefore ascribable to the solution of everyday issues, such as the calculation of the salary due to the workers employed in the construction of pyramids or ziggurats."

The extra letters appear randomly and may change position each time the document is reopened.

Additional Details:

• The issue occurs even without editing the document—simply opening and reading it is enough.
• OneDrive does not seem to be the cause, as the issue happens with both local and cloud-stored files.
• Screen readers (JAWS/NVDA) are likely not the cause, as the issue persists regardless of the voice used (JAWS voices, Microsoft neural voices, etc.).
• The issue disappears when the SAPI voice adapter is uninstalled.

System Information:

• Operating System: Windows 11 24H2 (OS build 26100.3194)
• Microsoft Word Version: Microsoft Word Subscription Version 16.0.18429.20158
• Screen Reader: NVDA 2024.4.1 and JAWS professional 2025.2412.50
• SAPI Voice Adapter Version: 0.2.3

Expected Behavior: Word documents should display normally without extra letters appearing.
Actual Behavior: Random sequence of letters appear in documents upon opening and reading them with a screen reader. The letters may move to different positions each time the document is reopened.

Notes:

This issue needs further testing both with local and OneDrive files, to determine the root cause.