There is a particular pleasure in hearing a book and seeing it at the same time. Your eyes run a little ahead, the narrator catches up, and a sentence you would have skimmed gets its full weight. Some big stores offer this, but only for books bought from them and only inside their own apps. This note is about doing it with books you own: an audiobook file and the ebook of the same edition, on an iPhone or iPad.
What you need
Two files, both DRM-free:
- The audiobook. An M4B is the tidiest, because it is one file with chapters inside. MP3s work too: a book that comes as numbered parts becomes one book with chapters. M4A, AAC, FLAC, WAV and AIFF also import, and so does the store’s .zip.
- The ebook, as an EPUB, of the same edition the narrator read. Not a PDF, not a Kindle file.
If you don’t have a pair to hand, skip to the last section: fifteen classics come with the app already synced, so you can see what you are aiming for before you import anything.
If you need to buy the files, the DRM-free catalogue lists stores that sell audiobooks and ebooks as files you keep, checked against each store’s own pages.
Step 1: Import the audiobook
Put the files somewhere your iPhone can see them: download them to Files, save them to iCloud Drive, or AirDrop them from a Mac. Then, in Voxlight’s Library or Books tab, tap + and pick the audio. For a book that comes as many MP3s, select all of them at once, or pick the zip.
Voxlight reads the title, author, narrator, cover and chapters from the files’ own tags. If any of that is wrong, fix it on the book’s page; it makes the next step easier.
Step 2: Add the EPUB
Open the audiobook’s page and add its EPUB. From now on the book has two halves: the narration and the text.
Step 3: Sync
Open the ⋯ menu on the book’s page and choose Sync Chapters. You get a choice of methods, and they trade time for precision:
| Method | Time | What you get |
|---|---|---|
| Chapter Sync | Instant | Audio chapters matched to text chapters by title. Chapter-level position, no highlighting. |
| Sample Sync | Minutes | Short clips across the book are written out and used as anchors. Approximate sentences. |
| Full Sync | Longest | The whole book, chapter by chapter, written out on your device. Sentence and word highlighting. |
| Manual Sync | A few minutes of yours | You link audio chapters to text chapters by hand. |
For reading along, Full Sync is the one you want. It runs on the iPhone itself; nothing is uploaded anywhere. It takes a while for a long book (roughly an hour per ten hours of audio on a recent device), but it is progressive: each chapter becomes usable as soon as it is done, and if it is interrupted it carries on from the chapter it was on. Keep the app open while it works.1
What reading along looks like
Open the book and play it. The sentence being read gets a soft wash, and the word being read is marked on top of it. In page mode the page turns by itself at the end; in scroll mode the text glides along.
Two things make it more than a karaoke trick:
- You can wander off. Stop listening and keep reading; the book is just a book. In the player, Read from Here opens the text at the narration, and in the reader Go to Playing brings you back to it.
- You can start from the page. With the audio paused, tap any sentence and the narration starts from that sentence.
When it doesn’t line up
Almost every bad sync is a mismatch between the two files, not a fault in the method.
- Different translations never sync. A recording of Constance Garnett’s Notes from Underground needs the Garnett text, not a newer translation.
- Abridged recordings skip text the ebook still has. Look for “unabridged”.
- Revised editions can drift: a new foreword, a moved chapter. Match the edition year or publisher where you can.
- US and UK spellings are fine. Colour and color still match.
If the highlight is in the wrong place, open the ⋯ menu, choose Re-sync Chapters and pick a stronger method. If Chapter Sync did nothing useful, the chapter titles probably didn’t match (numbers only, or missing); use Sample Sync, Full Sync or Manual Sync.
Try it before you import anything
Voxlight ships with fifteen public-domain classics, LibriVox recordings paired with Standard Ebooks editions, already synced: The Call of the Wild, The Time Machine, A Christmas Carol, Pride and Prejudice and more. Open one, press play and tap Read. That is what a good sync looks like, and it is a fair test of whether reading along is for you.2
More on those books, and on finding others like them, in Free public-domain audiobooks with the text to read along. The step-by-step version of this note is in the user guide: Pair an ebook and sync it.