Google NotebookLM Tests 30-Minute Lecture Audio Mode

• Google is testing a new "Lecture" Audio Overview mode in NotebookLM that can produce roughly 30-minute, single-host lectures.
• The mode appears alongside Deep Dive, Brief, Critique and Debate and pairs with a "Long" length option.
• A language selector and a British English narration voice (expected 2026) were spotted in recent builds.
• The feature is in testing; a sample lecture exists but public availability is unclear.

What Google is testing

Google’s NotebookLM is experimenting with a new Audio Overview format called "Lecture," according to strings and UI references found in a recent build. The format is described as a comprehensive, AI-generated lecture that explains and connects material across user-provided sources.

How the Lecture mode works

The Lecture mode appears to be offered alongside existing audio formats such as Deep Dive, Brief, Critique, and Debate. When users select the "Long" length setting, the mode is designed to produce an audio session of roughly 30 minutes delivered as a continuous, lecture-style monologue by a single host.

Intended pacing and style

Files and descriptions suggest the lecture will emphasize explanation and cohesion, linking multiple documents and sources into a listenable narrative rather than short summaries or back-and-forth debate. The pacing is positioned to suit deep review sessions rather than quick recaps.

Language options and narration

Notebooks in the build include a language selector tied to the Lecture mode, indicating the system could generate lectures in different languages based on user settings. Google also teased new narration voices, including a British English voice framed as arriving in 2026.

Use cases

NotebookLM’s Lecture Audio format is targeted at students, researchers, and professionals who want an immersive, listenable pass over dense source packs. Practical scenarios include exam preparation, pre-meeting briefings, and reviewing internal documentation while commuting.

Availability and limitations

The feature is currently in testing and not broadly available. TestingCatalog published a sample lecture generated from its sources to demonstrate pacing and structure, but Google has not announced a public launch date or wider rollout plan.

How it would fit into NotebookLM

If released, Lecture would likely appear in NotebookLM’s Audio Overview picker and follow the same workflow: users collect sources, choose the lecture format and language, then generate the audio. Output would be grounded in the selected documents, consistent with NotebookLM’s approach to sourced summaries and overviews.

For organizations and students that rely on audio study aids, a 30-minute AI-generated lecture with selectable voices and languages could make NotebookLM a more versatile study and briefing tool. Watch for official updates from Google on availability and voice options in 2026.