Beatline
The research
Binaural beats vs bilateral stimulation
21 July 2026
These two are confused constantly, partly because both involve your two ears doing different things. They come from unrelated places and are trying to do unrelated jobs.
What each one is
A binaural beat plays two steady tones at once, one per ear, a few hertz apart. Neither tone moves. The pulse is the difference between them, assembled by your auditory system.
The clearest way to tell them apart: bilateral stimulation is obvious the moment you hear it, and a binaural beat is not obviously anything until you notice the slow swell.
They come from different worlds
Binaural beats come from an acoustics observation, written up by Heinrich Wilhelm Dove in 1839, and later attached to the entrainment idea by people selling recordings.
Bilateral stimulation comes from EMDR, a psychotherapy for trauma developed in the late 1980s. In EMDR the alternating stimulus - originally eye movements, later also tones or taps - accompanies structured therapeutic work with a trained clinician.
That origin is the important part, and it is what makes the comparison awkward.
Why we do not offer bilateral stimulation
We are not going to grade the EMDR literature here, because it is a clinical question about a therapy and this is an app that makes sounds. But two things are worth saying plainly.
First, whatever bilateral stimulation does in EMDR, it does as one component of a structured protocol delivered by a clinician. The alternating tone is not the treatment. Extracting it and looping it through headphones is not a smaller dose of therapy; it is a different thing that shares an audio characteristic.
Second, and more practically: trauma processing without support can go badly. An app that hands you a stimulus associated with trauma therapy and no clinician is in a position we do not want to be in, and no amount of caveat copy fixes it.
So Beatline has no bilateral stimulation mode. Not because we assessed it and found it wanting, but because it belongs to a setting we are not part of.
If you are choosing between them
If what you want is something to work, sleep or settle to, that is what binaural beats and the rest of this app are for, and the evidence is what it is: Garcia-Argibay, Santed and Reales 2019 found a medium pooled effect on anxiety, attention and memory across 22 studies, while Ingendoh 2023 found 8 of 14 studies contradicted the mechanism usually offered to explain it. Modest outcomes, contested story.
If what you want is help with trauma, please talk to a clinician rather than an app. That is not a disclaimer we are obliged to print. It is the actual right answer, and an alternating tone bought from anyone is not a substitute for it.
If you want the slow left-right movement purely because you find it pleasant, that is a real preference and nothing here argues against it. It is just not something this app does, and not something we would file under evidence.