Or a standard viva pause.
Just long enough to check you’ve understood a question, begin to consider what it means and get some thoughts in order for what you might say.
Three to five seconds is a pause – but if you need longer, take longer. There’s no rush in the viva. If you need to think more or consult in your thesis then tell your examiners.
Pause when you need to in the viva. Take your time to engage as well as you can.