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These three get sold as the same thing constantly. They are not. They work differently, they come from different places, and the evidence behind each is in a completely different state.

Knowing which is which will save you money, and it will make you much harder to sell to.

Bilateral audio

A sound that pans across the stereo field — left ear, right ear, left ear — usually slowly. You need headphones for it to be anything at all.

It comes out of EMDR, the trauma therapy Francine Shapiro described in 1989, where a person recalls a distressing memory while following an alternating left-right stimulus [1]. That is the entire lineage. Alternating audio is one of the stimulus options a therapist can use inside a structured eight-phase protocol.

Evidence status: genuinely shaky once you separate the audio from the therapy. Where alternating tones have been tested against eye movements head to head, the tones came off worse [3]. The biggest dismantling trial found that fixating on a stationary hand worked just as well as tracking a moving one — so the left-right part may not be the active ingredient at all [2]. A review of 76 trials concluded there is not enough evidence to recommend EMDR for anything other than PTSD [4]. And a systematic search for research on self-administered EMDR found a single small study [8].

What it is reasonable to expect: a slow, moving sound that is easy to rest your attention on. Nothing in the literature supports the hemisphere-balancing story.

Binaural beats

A genuinely different mechanism, and the confusion between the two is the single most common error in this space. Binaural beats play two steady tones at slightly different frequencies, one in each ear — say 200 Hz and 210 Hz. Nothing moves. Your auditory system perceives a third, phantom pulsing tone at the difference between them, in this case 10 Hz. The claim is that your brainwaves then entrain to that frequency.

Bilateral audio moves a real sound between your ears. Binaural beats hold two different sounds still and let your brain manufacture a third. Different intervention, different proposed mechanism, separate evidence base. Evidence for one says nothing whatsoever about the other — which does not stop marketing copy citing binaural beats research to sell bilateral audio, or the reverse.

Evidence status: more actual trials than bilateral audio has, and more mixed. Reviews report signals for anxiety in specific settings — a 2025 meta-analysis looked at perioperative anxiety and pain [5], and a 2026 systematic review covered anxiety, sleep and cognition in young adults [6]. The literature is heterogeneous and methodologically weak, with small samples and inconsistent protocols. Something may be there. It is not settled.

White noise

The least glamorous and the most straightforward. A flat spread of sound across all frequencies. Pink and brown noise are the same idea weighted toward the lower end, which most people find less harsh.

There is no theory of brain states here. White noise masks. It raises the acoustic floor so that the car door, the neighbour’s TV and the creaking pipe do not stand out against silence and pull your attention. That is the whole mechanism, and it is the only one of the three where the mechanism is not in dispute.

Evidence status: mixed for sleep, and often overstated, but the underlying idea — masking makes intrusive sounds less noticeable — is not controversial. If you live somewhere noisy, this is the one to try first, and it is free.

Which to reach for

If the problem is noise — traffic, a housemate, a snoring partner — use white or pink noise. It is the right tool and you do not need headphones.

If the problem is a racing mind, any of the three might help, and probably for the same unglamorous reason: you have given your attention something predictable to hold onto instead of the 3am thought. That is a real effect. It is just not the exotic one.

If someone is telling you their audio balances your hemispheres, resets your nervous system or mimics REM sleep, they are describing a hypothesis as though it were a finding. The most thorough review of EMDR’s proposed mechanisms lists the REM analogy as speculative with limited empirical validation [7], and the interhemispheric account is the weakest of the lot.

What we say about ours

Unwind is bilateral audio: sound that moves gently between your ears. We built it because people find it settling, and we are not going to dress that up as a mechanism nobody has demonstrated.

MoodFire is not therapy and Unwind is not EMDR. If you are working through trauma, that belongs with a trained clinician rather than a track on your phone.

The useful test for any audio product: ask what it claims and then ask who measured it. In this corner of the market, the answer is often nobody.