Google NotebookLM testing new 30-minute 'Lecture' mode for deep learning

Google is enhancing its AI application, NotebookLM, by testing a new “Lecture” format for its Audio Overviews, along with a future British accent option.

The new Lecture format, spotted by TestingCatalog in an app teardown, differs significantly from existing Audio Overview styles, such as “Deep Dive” or “Debate.”

Instead of a discussion between two AI hosts, Lecture employs a single narrator to deliver a continuous, scholarly explanation. When paired with the “Long” duration setting, these lectures can last up to 30 minutes.

The primary distinction is the tone. The format is designed to be calm and explanatory, connecting complex ideas across a user’s sources rather than providing a quick summary or a staged debate. This makes it ideal for extended listening—such as during a commute—for students and researchers trying to grasp dense material without staring at a screen.

TestingCatalog has already generated a full 30-minute sample, suggesting this is a planned fifth mode rather than a hidden experiment.

In addition to the new format, Google is set to introduce British English narration voices in 2026. The company teased the update on X (formerly Twitter) with the very British phrase, “you’ll be absolutely chuffed.”

A preview of this voice technology is already available in a Featured Notebook titled “Archive 1945,” created in collaboration with The Economist. While the Lecture edition is still in the testing phase and has no official release date, the working demonstrations suggest the feature is being actively prepared for launch.