Headphones or speakers?

The short version: it depends on the mode, and the default mode does not need headphones.

The rule

Ask one question — is the beat in the sound, or in the comparison between your ears?

• In the sound (isochronic, monaural, phase-amplitude coupling): speakers are fine. A phone, a laptop, a kitchen radio. The rhythm is a genuine change in loudness and any transducer reproduces it.
• In the comparison (binaural, poly-rhythmic): headphones are mandatory. Not recommended — mandatory. On a speaker the left and right signals mix in the air before they reach you, and the effect has nothing left to be built from.

That is the whole rule. Everything else is preference.

Why "recommended" is the wrong word for binaural

It is worth being blunt, because a lot of writing on this is mushy. If you play a binaural session on a speaker, you do not get a weaker version of the effect. You get two steady tones and no beat whatsoever. The thing the session is named for is absent.

This is why every session that offers binaural also says so, and why the player shows a headphone indicator the moment you switch into a mode that depends on stereo separation — and pauses if your headphones are removed mid-session.

The setting that silently breaks binaural

Worth checking before you conclude binaural does nothing for you: mono audio.

Both iOS and Android have an accessibility option that combines the left and right channels into one identical signal, sent to both ears. It is genuinely useful — for people with hearing in one ear, or using a single earbud — and it is easy to have switched on and forgotten.

It also eliminates binaural beats completely. If both ears receive the same summed signal, there is no interaural difference left to compare, and the effect cannot form. Exactly the same failure as playing it on a speaker, but invisible, because your headphones are on and the audio sounds fine.

On iOS it is Settings → Accessibility → Audio & Visual → Mono Audio. On Android, Settings → Accessibility → Mono audio. Any session in an isochronic, monaural or phase-amplitude mode is unaffected.

Where headphones still help

Even on modes that do not require them, headphones do two useful things.

They deliver the low end. A large part of this catalog runs carriers between 80 Hz and 200 Hz with a brown or sub-weighted noise bed. Laptop speakers roll off steeply below about 200 Hz, which means a meaningful part of what you are meant to be hearing simply is not being produced. The session still works — the modulation is intact — but it sounds thinner than it should.

They exclude the room. Part of the point of a noise bed is masking. A speaker adds your room's sound to the mix; headphones replace it.

Where speakers are genuinely better

For sleep, speakers are often the right answer, and not as a compromise. Sleeping in earbuds is uncomfortable, works loose, and for some people is a genuine ear-health issue over hours. A quiet speaker across the room delivering an isochronic session at low volume is a better night than good headphones you take out at 2 a.m.

The same goes for anything you are doing with your body — breathwork, stretching, recovery — where being tethered is the problem.

A note on volume

Whatever you use, start quieter than feels right. These sessions are built to sit underneath attention rather than on top of it, and the most common first-session mistake is arriving from music streaming with the system volume set for something far louder. If you are straining to hear detail, it is loud enough.