If the cut-outs are always at the beginning of words, and he's using Bluetooth audio, it's the Bluetooth Audio that is the problem.  There is an NVDA Add-on, BluetoothAudio, that is meant to remedy this issue.  If it doesn't work, there is another alternative in a program called Silenzio, but it makes sense to try the add-on first.
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Brian - Windows 10 Pro, 64-Bit, Version 1909, Build 18363  

Power is being told you're not loved and not being destroyed by it.

       ~ Madonna