What a viva voce is, and why it decides the category of pass

A viva voce ("by living voice") is an oral examination of your thesis by two or more academic examiners. In the UK and most European universities it is mandatory and binding: a doctorate cannot be awarded until you defend in person. Outcomes are tiered across five recommendations, from pass with no corrections through minor corrections, major corrections and re-submission to fail.

Analysis of 26,076 PhD candidates across 14 UK universities between 2006 and 2017 found that 96% passed. Among those who passed, only about 5% needed no amendments, 79% received minor corrections and 16% major corrections. Only 3.3% failed outright, and of those, around 97% were offered an MPhil rather than nothing at all. The viva is rarely where doctorates die, but it is almost always where the category of pass gets decided.

The format is genuinely different across systems

In the UK the viva is closed-door, mandatory, usually run by one internal and one external examiner, and lasts between 1.5 and 3 hours. In Australia an oral defence is less common, because Australian PhDs have historically been examined by written reports from external reviewers alone, although some universities have made the oral defence compulsory. In Vietnam the defence is typically open and public, with a panel of five to seven reviewers and an audience.

The implication is operational rather than cultural. If you are in a programme that does not require an oral defence, your written thesis carries the entire weight and there is no second chance to clarify a weak chapter. If you are defending publicly in front of a panel that includes non-specialists, rehearsing in a closed two-examiner format will not prepare you for the questions you actually get.

The first ten minutes

Three opening questions account for roughly 80% of viva starts: could you summarise your thesis in five minutes, why did you choose this topic, and what is your contribution to knowledge. Examiners are not trying to catch you out. They are listening for clarity, confidence, and whether you can articulate your core contribution in your own words without reading from the thesis. A strong answer names the topic, the method, the key finding and its significance in under 300 words.

A practical drill: break the five-minute summary into four blocks of problem, method, finding and significance, and give each a 90-second budget. Candidates who do this typically land between four and five minutes instead of drifting past ten.

Three moves when you do not understand a question

For candidates working in a second language, this is the single most useful skill in the room, and it should be learned in this order.

1. Ask for thinking time. "Could I take a moment to think about that?" A silence of five to ten seconds reads as professional, not weak.
2. Paraphrase the question back. "If I understand you correctly, you are asking whether…" and let the examiner correct you.
3. Ask for an example. "Could you give me an example of what you mean?"

None of these moves costs marks. Examiners expect candidates to paraphrase difficult questions, and asking for a question to be repeated or rephrased is a sign of careful engagement rather than weakness. Candidates who use the paraphrase move stop guessing, which is where most avoidable damage happens.

How long an answer should be

Use a length budget. Factual or definitional questions take 60 to 90 seconds. Critical-analysis questions, of the "why did you choose X over Y" kind, take two to three minutes. Yes/no and clarification questions take 30 seconds. A pause of three to five seconds before answering reads as considered; a pause beyond 15 seconds reads as panic, and the way out of it is the paraphrase move.

The most common mistake first-time candidates make is over-answering: talking past the point of value and inviting follow-up challenges. Examiners tend to form their judgement on the first 60 to 90 seconds of an answer, and everything after that is the candidate either reinforcing or unwinding the case.

Practising when your supervisor is not a native speaker

Build a three-part drill. First, a mock viva with two examiners independent of your supervisor, one in your field and one outside it, so you meet the cross-disciplinary push-back real examiners use. Second, self-record yourself answering 20 test questions and listen back for filler words and overlong answers. Third, a 60-minute session with a peer from outside your field who has to understand your contribution from your spoken explanation alone.

The out-of-field examiner role carries the highest value, because it forces you to strip jargon and explain your assumptions in plain English. A useful test question: can you explain your central technical term in one sentence you could say to a family member?

Handling push-back

A hostile examiner is not the same as an unfair one, and push-back is a normal part of the viva. Three rules hold. Concede minor points early and specifically. Hold the line on your main findings, but back the hold with evidence from your own chapters. Never argue: close any contested exchange with a version of "I appreciate that perspective, and here is how I weighed it", then stop talking.

The danger zone is not push-back itself. It is capitulating on every point, which looks as though the thesis was not yours, or refusing all push-back, which looks defensive and unscholarly. Examiners read concession-and-defence as a marker of doctoral maturity.

Read the full lesson

This unit is a condensed version. The full lesson, with worked examples and the source list, is published open access by MAAS Education Technology JSC: How do you prepare for a viva voce defence when English is your second language?

A citable snapshot with a permanent DOI is archived on Zenodo: 10.5281/zenodo.22292953.

Licence: CC BY 4.0. Generative AI tools assisted with drafting and structuring the text, subject matter, worked examples and sources were directed by MAAS Education Technology JSC, and the final text was reviewed and approved by MAAS editors before publication.