Compare · Text-to-speech reader for PDFs
Aethel Audio vs Audeus
Audeus is a text-to-speech reader for students: it reads PDFs and documents aloud with word-by-word highlighting, can skip citations and headers, and includes annotations and an AI chat about the document. Aethel shares the study focus and specialises further in technical material: equations are rebuilt and spoken as maths, and figures and tables are described. For prose-heavy courses Audeus covers more platforms. For courses built on formulas, compare one chapter in both.
Last reviewed 11 November 2026. Audeus is a product of Audeus; this page is not affiliated with or endorsed by Audeus. Something out of date? Tell us and we will correct it.
Side by side
What it is
Audeus: A text-to-speech reader for PDFs and documents, aimed at students
Aethel: A study reader for technical books and research papers
Highlighting
Audeus: Word-by-word highlighting
Aethel: Sentence-by-sentence highlighting; tap a sentence to continue from it
Equations
Audeus: General-purpose narration; equation handling isn't a documented feature
Aethel: Each equation rebuilt and read as maths; the printed formula stays on screen
Figures and tables
Audeus: Focus is on narrating the text
Aethel: Kept beside the paragraph that cites them, with a spoken description
Study tools
Audeus: Annotations and an AI chat about the document
Aethel: Ask about a passage, review cards, highlights exported as Markdown
Where it runs
Audeus: iOS and Android apps, and Chrome and Edge extensions
Aethel: Web app on any device, installable, with offline downloads
Price
Audeus: See Audeus's current prices
Aethel: Free: 5 books and 1 hour of narration. Pro Reader $4.99/month (6 h, standard voices). Pro $9.99/month (12 h, ElevenLabs voices). Yearly plans save about two months. All plans
Choose Audeus if…
- • You want word-by-word highlighting.
- • You want a browser extension that reads web pages aloud.
- • Your reading is mostly prose and you want one app for all of it.
Choose Aethel if…
- • Your courses are built on equations, figures and tables.
- • You want review cards made from each chapter.
- • You want a chapter translated into one of 17 languages and narrated.
Test it on your hardest page
The fairest comparison is your own material. Import the same maths-heavy chapter into both and listen to a page with equations. Here is what Aethel says for a classic:
Attention(Q, K, V) = softmax(QKᵀ / √dₖ)V
Aethel says
Attention of Q, K, V equals softmax of the quantity Q K transpose over the square root of d sub k, times V
Vaswani et al., “Attention Is All You Need”, NeurIPS 2017, equation 1
Questions
Both are for students. What is the real difference?
Scope. Audeus is a general study reader for any PDF. Aethel is narrower and deeper: it is built for technical subjects, where reading the equations and describing the figures decides whether the audio is usable.
Which should I use for a statistics or physics course?
Try a chapter with formulas in both and listen to what happens at the first equation. That one test usually settles it.
Other comparisons
Hear your own book this way.
Free to start: five books and an hour of narration, no card needed.