Google's working on a lot of different AI tools in Google Labs, its experimental playground, but none have taken off as much as NotebookLM. And there’s one feature that deserves most of the credit for its viral success: Audio Overviews.
Though Google first announced the feature in September 2024, it hasn’t seen many major improvements since then. The biggest changes so far have been support for more languages beyond English and the option to choose between Shorter, Default, and Longer versions. Well, the Audio Overviews feature has finally received what I’d consider its biggest update since launch.
A couple of days ago, the NotebookLM team announced via a X (formerly Twitter) post that it's rolling out new Audio Overview formats. The team followed up with another post that the new formats have now been rolled out to all users in all languages. So, of course, I had to immediately try them out and see how they fit into my workflow.
What new Audio Overview formats are now available in NotebookLM?
Brief, Critique, and Debate
With this update, NotebookLM gets three new Audio Overview formats: Brief, Critique, and Debate. Before Google introduced these new formats, the only option available was the default Deep Dive format, which NotebookLM describes as a "lively conversation between two hosts." You can try these Audio Overview formats by heading to the Studio panel, clicking the pencil icon in the Audio Overview section, and then selecting your desired format.
It's essentially an engaging podcast, and it’s hands-down been my favorite way to get a quick yet comprehensive understanding of my sources. However, since I’ve been using the Audio Overview feature almost daily since it first launched, it’s honestly started to feel a bit repetitive. That’s why these new formats immediately caught my attention.
Though NotebookLM's team didn’t mention it in the X post where they announced the update, the new Audio Overview formats also include something users (myself included) have been waiting on forever: new NotebookLM voices. So, it’s another thing to be genuinely excited about if you’ve been using Audio Overviews regularly.
Unfortunately, though the new Audio Overview formats have been rolled out in all languages, you don't have any control over the length of the output. With the default Deep Dive format, you can choose between Shorter, Default and Longer. However, you're only limited to the Default length with the new formats.
The Debate mode is perfect for exploring both sides of any topic
Perfect for understanding every perspective
I primarily rely on NotebookLM for studying since my major includes a fair share of memorization-heavy subjects like history and law. When I used the Deep Dive Audio Overview format to study these subjects, it felt a bit too much like listening to two people casually discussing the material.
When NotebookLM announced the Debate mode, I instantly knew it'd be perfect for courses and topics where I'd need to dig into opposing viewpoints and remember arguments more effectively. Given I’m currently on summer break, and I’m not enrolled in a course I feel would be a perfect fit for Debate mode, I decided to test it out on one of my own articles instead. Of course, I chose an article where I was presenting a clear argument, since that felt like the closest substitute for a debate-heavy course topic. So, I used my article about comparing the Copilot Mode in Microsoft Edge to Perplexity's Comet browser.
As expected, NotebookLM did what it promised, with one host tackling the strengths of Edge’s Copilot Mode and how it's better (which is the same argument I made in my article) and the other favoring Perplexity's Comet and how it might be a stronger option depending on the context. What I found really impressive is how, even though my article didn't cover two opposing points and only focused on Edge’s Copilot Mode, NotebookLM still managed to generate a balanced debate by pulling in counterarguments and presenting them in a way that felt natural.
For instance, the male host, who was on Comet's side, mentioned the first point I made: that Copilot Mode feels more like a natural extension of the browser itself rather than just an add-on. The host intelligently went over all the points I raised and clearly explained why they made Copilot Mode the stronger choice. Both hosts had an engaging back-and-forth, and each made points that felt well-reasoned and complementary rather than forced.
They also managed to string together answers to questions one dropped into the conversation, with the other picking them up seamlessly and adding a counterpoint. For example, one point I made in the article was how I wasn't a fan that Comet had Perplexity as its default search engine. The host favoring Copilot made the same point, and the other host countered with the fact that the default engine can be changed if you prefer something else.
Both hosts extracted examples mentioned in my article, which I know will be extremely helpful for the times when I'm using this format to study. Instead of just passively listening, I’d be able to hear arguments and counterarguments framed in a way that pushes me to think critically about the material. I also noticed that the hosts expanded on points I made by including examples of their own, which really made the debate feel richer and more engaging. It didn’t just sound like they were parroting back my article and felt like they were building on it.
The Brief Overview is ideal when you need an extremely quick summary
When you need a lightning-fast recap
👁 Swift for Beginners Brief Audio Overview format
Even if you're not a student anymore, you probably remember the moment when you had just two minutes before an exam and felt like you were forgetting everything you’d spent the past few weeks learning. I know that feeling all too well, and the Brief format is perfect for exactly those moments. As the format's name suggests, it produces bite-sized overviews that are between one to two minutes long, giving you a super quick refresher without overwhelming you with details.
Unlike the typical Audio Overview Deep Dives or the Debate format, this overview is hosted by a single voice, making it concise, straightforward, and easy to follow in record time. For instance, I'm currently learning more advanced Swift using NotebookLM, and I wanted to hear a quick recap of everything I've learned so far. A podcast-style discussion hosted by two people, which would typically last several minutes, felt like overkill, and the Brief format gave me exactly what I needed — just the essentials, fast and clear.
The Critique Overview is perfect for getting expert feedback on your material
Like having a professor give expert feedback on your work
👁 Mastering Modern Swift Critique Audio Overview format
Ever wanted to know how something you’ve worked on would be evaluated before sending it to your instructor or your boss? As someone who overthinks every possible thing and anxiously waits for feedback, I know I have.
Well, the Critique Overview is designed for exactly that. It provides an expert-style review of your material, highlighting strengths, pointing out weaknesses, and offering constructive suggestions to help you improve. After a quick hello and welcome, the hosts immediately said:
Let's jump into the feedback. We've looked at your material, and there's some good stuff here, and well, areas we can refine.
And then it immediately began explaining how the content within the sources I uploaded in the notebook could have been better. I generated the Critique Overview of the same notebook I'm using to learn Swift, and it managed to analyze topics my sources only briefly mentioned instead of providing in-depth explanations.
It highlighted areas where my sources skimmed over important concepts and suggested ways to expand or clarify them. Rather than just pointing out what was missing, it offered actionable guidance on how to improve my understanding and make my notes more complete. The hosts explained how examples and explanations could be better and even suggested additional analogies to make complex topics easier to grasp.
By the end, I had a clear sense of what needed more attention and how to approach it, making the Critique Overview feel like having a personal tutor review my work.
The reason I tried the Critique Overview and the Brief with the same example was that I wanted to see how they truly differ. Though the Swift notebook isn’t what I expect to be using this format for, I will use it for essays I’d like to polish or projects I want to refine before submission. The Critique Overview is ideal for work that benefits from detailed feedback, helping me catch gaps, improve explanations, and strengthen the overall quality of my material.
The update I've been waiting for
Though NotebookLM's got dozens of updates in the past few months and has introduced great features like Mind Maps and Video Overviews, the Audio Overviews feature is still my most-used feature. So, I'm thrilled Google finally added new formats!