The advice to "read along while listening" gets repeated often enough in language-learning circles that it's worth asking what it actually does, because the honest answer is that it helps with some things and gets in the way of others, and which one depends on what you're trying to build that day.
What dual input genuinely does well
Pairing audio with the matching text is one of the more reliable ways to connect how a word is written with how it actually sounds when spoken at natural speed. This matters more than it seems, because a lot of learners can read a word confidently and still fail to recognize it when they hear it spoken quickly in connected speech, where sounds blend and reduce in ways that written form doesn't show. Reading along while listening closes that specific gap directly, because you're mapping the two representations at the same moment rather than separately.
It's also useful for picking up natural sentence rhythm and stress patterns, which text alone can't teach you at all. Punctuation gives you a rough guide to pauses, but it doesn't tell you which words a speaker emphasizes or how intonation shapes meaning, and hearing that alongside the text you're reading builds an intuition for it that reading in silence never will.
Where it works against you
Comprehension speed is the main casualty. When you're following along with audio, your reading pace is locked to the speaker's pace, which removes your ability to slow down on a hard sentence or reread a clause you didn't catch. If the audio is faster than your comfortable reading speed, and for most learners below an advanced level it usually is, you end up either falling behind the audio or skimming the text without actually processing it, neither of which builds the kind of deep comprehension that slower, self-paced reading does.
There's also a subtler cost: dual input can quietly turn into passive listening with the text as a security blanket, where your eyes are moving across the page but the actual work of parsing meaning is being done by your ears, if it's being done at all. This is comfortable and can feel productive without doing much for reading skill specifically, because reading skill depends on your eyes and brain doing the parsing work unassisted.
A practical way to use both without the downsides
Rather than treating dual input as a default mode, use it for a specific, narrow purpose: after reading a piece on your own first, at your own pace, with normal look-ups where needed, go back and listen to the audio version once while following the same text. At that point you already know the meaning, so the exercise is purely about connecting sound to the words you've already comprehended, which is exactly the thing dual input is good at, without the comprehension-speed problem that comes from doing both at once for the first time.
This sequence, read first, then listen along, gets you the pronunciation and rhythm benefit without sacrificing the deep, self-paced comprehension work that silent reading does better. Doing them simultaneously from a cold start tends to produce a shallower version of both skills rather than a genuine combination of their strengths.
When to just pick one
If your specific goal that session is building reading speed or working through genuinely difficult text, skip the audio entirely and read at your own pace. If your goal is listening comprehension or pronunciation, audio alone, without the crutch of text, forces your ear to do the work it eventually needs to do without support. Dual input is a specific tool for a specific gap, connecting known written vocabulary to its spoken form, not a universal upgrade over either skill practiced on its own.
Why the advice to combine them persists anyway
Part of why "read along while listening" keeps circulating as universal advice is that it feels productive in the moment, you're doing two things at once, which reads as efficient. But language skills aren't always additive that way. Two moderately effective activities done simultaneously can produce a result weaker than either one done well on its own, especially when one of them, following audio at natural speed, sets a hard pace ceiling on the other. It's worth being skeptical of any language-learning technique whose main appeal is that it feels efficient, and checking instead what specific gap it closes and whether that's the gap you actually have right now.
A version worth trying once you're more advanced
Once your reading speed genuinely approaches natural speaking pace in the language, simultaneous audio and text stops being pace-limited in the same way, and at that stage, dual input from the start can work well, since you're no longer racing to keep up. This is one of the reasons the same piece of advice can be genuinely right for an advanced learner and genuinely counterproductive for someone still working through B1-level text: the technique doesn't change, but whether your reading speed can actually support it does.