Isochronic tones: a generator that works without headphones

What are isochronic tones

The word means “of equal time”. An isochronic tone is a single tone that is switched on and off at equal intervals: sound, silence, sound, silence. If this happens ten times a second, you hear a 10 Hz pulse.

Unlike a binaural beat, nothing has to be assembled in the brain. The rhythm is in the air, so both ears hear the same thing, and a speaker works as well as headphones.

The sound is more noticeable than a binaural beat. Where a binaural beat wavers softly, an isochronic tone ticks. Some people find that easier to follow, others find it tiring.

How isochronic tones are made: pulses, ramps and why a speaker is enough

An isochronic tone has two settings. The carrier is the pitch you hear; the pulse rate is how many times a second it switches on. A 220 Hz tone pulsing at 10 Hz is a hum that sounds for a twentieth of a second, falls silent for a twentieth of a second, and repeats.

The shape of each pulse matters as much as the rate. If the tone is cut on and off instantly, every edge makes a click and the pulse sounds harsh. A short fade in and fade out, called a ramp, removes the clicks. The longer the ramp, the rounder and gentler the pulse; when the fades fill the whole cycle, the sound simply swells and ebbs, much like a monaural beat.

The generator on this page keeps the tone on for half of every cycle and off for the other half, and rounds the edges with a smoothing filter that follows the pulse rate. At slow rates you hear separate soft beeps; as the rate climbs, the beeps merge into a ticking, then a rattle, then a buzz.

Because the switching happens in the sound wave itself, any speaker that can play the carrier can play the pulse. This is why a 40 Hz isochronic tone works on a phone while a 40 Hz pure tone does not: the phone has to reproduce a 220 Hz tone switched 40 times a second, not a 40 Hz hum, which small speakers cannot produce. It is also why both ears hear the same rhythm, and why the pulse survives hearing loss in one ear.

One rule follows from the timing in the table below: keep the carrier well above the pulse rate. At 40 Hz each burst of sound lasts 12.5 thousandths of a second, which holds fewer than three waves of a 220 Hz tone, so the pitch blurs into a buzz. A carrier of 300 to 400 Hz keeps more of the tone; in a 2021 study of 40 Hz isochronic tones the researchers used 440 Hz, on for half of each cycle, with a minimal ramp.

Isochronic tones vs binaural beats vs monaural beats

There are three ways to put a slow rhythm into sound.

Two studies compared the first two types directly. In Canada a 40 Hz beat mixed into one ear evoked a larger brain response than the same beat presented binaurally. In a later study in Montreal both types entrained the cortex, and the monaural beat did so more strongly. Isochronic tones belong to the same family as monaural beats: the rhythm is physically present.

How the binaural kind works, and what its larger body of research shows, is on the page “Binaural beats”.

Do isochronic tones work: what research exists

The honest answer has two parts.

The first part is solid. The hearing system follows a sound that pulses at a steady rate, and the response can be recorded from the scalp. It was described in 1981 and has been used in hearing tests ever since. It is strongest when the sound pulses about 40 times a second.

The second part is thin. Whether listening to isochronic tones improves sleep, focus or mood has been tested in very few controlled studies, far fewer than for binaural beats. A review of auditory beat stimulation published in 2015 found contradictory results even for binaural and monaural beats and pointed to the differences in frequency, duration and task as the reason.

A handful of newer studies fill in a little. At Université Lyon 1 in France, 28 people listened for four minutes each to gamma binaural beats, white noise and a newer sound modelled on isochronic tones while their EEG was recorded. All three raised power in the gamma band, but the isochronic-style sound raised it most, and only it made alpha power fall steadily over the four minutes. The first author is also affiliated with a private company in Lyon, and four minutes in a laboratory say nothing yet about sleep, focus or mood.

Studies that measured outcomes are mostly negative so far. In New York, 11 trained cyclists heard their own music with or without a 40 Hz isochronic tone before 7-minute rides, and neither their power output nor how energised they felt changed. In Turkey in 2026, isochronic tones during wisdom-tooth surgery did not lower anxiety compared with silence. No meta-analysis of isochronic tones exists, and no review has pooled their EEG studies the way a 2023 review did for binaural beats, which found the brain following the beat in five of 14 studies and not in eight.

So the benefits of isochronic tones are best described as plausible: the mechanism is measured, the everyday effects are mostly inferred from research on other kinds of beats. That is a reason to try them and judge for yourself, not a reason to expect a cure.

Isochronic tones benefits: what you can expect

Setting research aside, here is what listeners can check for themselves.

• A clear rhythm to follow. For people who find a binaural beat too faint, the pulse is easier to notice and to return to.
• No headphones. This matters in bed, in a shared room and for anyone who dislikes wearing them.
• Works with hearing loss in one ear. A binaural beat needs two ears that hear well; an isochronic tone does not.
• A steady background. Like a metronome, a pulse gives structure to a session of work or breathing.

What you should not expect is a guaranteed change of state. If a session leaves you calmer or more alert, keep the setting; if it leaves you irritated, change the rate or the carrier, or stop.

Isochronic tones for sleep, focus, anxiety and meditation

The pulse rate is chosen by the state you are after, in the same way as for binaural beats. The bands themselves are explained on the page “Brain waves”, and each has its own page: delta, theta, alpha, beta and gamma waves. Keep in mind that a rhythm the brain shows in a certain state is not a switch that a sound can flip.

For sleep isochronic tones have one practical advantage: you do not have to wear headphones in bed.

Isochronic tones for sleep and deep sleep

Sleep is where the lack of headphones helps most. Place the phone or a speaker at arm's length from the pillow, not under it, and set the volume so that you have to listen for the pulse to hear it.

Choose a 2 Hz pulse on a low carrier of 120 to 180 Hz and a 30-minute timer. A low carrier makes the pulse round and dull, which is what you want at night. If the ticking keeps you awake instead, the rhythm is too sharp for you: switch to a binaural beat with sleep headphones or to plain pink noise.

No controlled trial has tested isochronic tones alone for sleep. The closest study, from the All India Institute of Medical Sciences in Bhopal in 2026, gave 26 medical students one delta session through a commercial headset that combined music, a guided meditation, binaural beats, isochronic tones and flashing lights. Their smartwatch sleep figures were better after the session than before. There was no control group, sleep was measured by a consumer watch, and the authors themselves write that the design cannot show cause and effect. With five ingredients at once, it also cannot tell you what the isochronic tone contributed.

Binaural beats have more sleep research: in a pilot study, 20 students fell asleep faster after a week of delta beats, while in a double-blind trial of 43 people with mild insomnia, music with and without beats improved sleep equally. The details are on the page “Binaural beats for sleep”, and what delta activity really is during deep sleep is on the page “Delta waves”. The practical conclusion is the same for both kinds of sound: treat the pulse as a calm signal for winding down, next to darkness, a cool room and a regular bedtime.

Isochronic tones for anxiety and stress: what the only trial found

Isochronic tones are often sold for anxiety, and only one randomised trial has tested that. At Afyonkarahisar Health Sciences University in Turkey, 90 patients having an impacted lower wisdom tooth removed were split into three groups of 30: isochronic tones during the operation, binaural beats, or no sound. Anxiety was measured with four questionnaires before and after surgery, and pulse, blood pressure, breathing rate and oxygen saturation were recorded at eight stages.

The questionnaires showed no difference between the three groups. There were a few isolated differences in the body measures: breathing rate at the moment of anaesthesia was lowest in the isochronic group, blood pressure at the incision lowest in the binaural group. Even so, 78.3 % of the patients who listened said they would want sound again at their next dental treatment. The authors' conclusion is plain: a limited effect and no definitive anxiety-relieving benefit.

Two things keep this result in proportion. Oral surgery is a hard test for any calming sound, and one trial is one trial. Binaural beats, by contrast, showed a medium effect on anxiety in a 2019 meta-analysis of 22 studies, and in a UK hospital they reduced anxiety before day surgery. Whether isochronic tones would do as well in such settings has simply not been tested.

• For everyday stress, choose an alpha pulse of 10 Hz on a soft carrier of 150 to 200 Hz, at a low volume.
• Pair it with slow breathing: in for a count of four, out for a count of six, for 10 to 15 minutes.
• Start before the stressful moment, not during it: in binaural beat studies listening beforehand worked better.
• If the sharp pulse makes you more tense, switch to the binaural mode or to plain noise. A sound that irritates you will not calm you.
• Anxiety that disrupts sleep, work or relationships is a reason to see a doctor or psychologist; a sound is not a treatment for an anxiety disorder.

Alpha beats for calming down, and the studies behind them, are covered in detail on the page “Binaural beats for anxiety”.

Isochronic tones for focus and for meditation

For focus the pulse works like a metronome. A rate of 15 to 20 Hz on a carrier of 250 to 300 Hz, played quietly, marks time without asking for attention. Start it before the task, as with binaural beats.

For meditation a slow pulse of 6 Hz gives attention an object. Count nothing; notice the pulse, notice when you have left it, come back. Because the rhythm is obvious, beginners often find an isochronic tone easier than a binaural beat, and experienced meditators often find it too intrusive.

Why theta and alpha for meditation? Because meditation itself tends to change them. A systematic review of 56 EEG studies with 1,715 people found that mindfulness meditation most often goes with more alpha and theta activity than rest with the eyes closed, though not in every study, and showed no consistent pattern for beta, delta or gamma. The pulse rate borrows those numbers from meditators; it does not create their state. Use it as an anchor for attention, and let the practice do the rest. More on these rhythms is on the pages “Theta waves” and “Alpha waves”.

40 Hz isochronic tones and gamma waves

Of all the rates on this page, 40 Hz is where isochronic tones have the firmest footing. A tone switched on and off 40 times a second is close to the classic stimulus of hearing research: in 1981 Robert Galambos and colleagues found that sounds repeated about 40 times a second make the brain answer with one stable 40 Hz wave, and a later review of the method confirmed that in awake people this response is most prominent near 40 Hz. A binaural beat at 40 Hz produces a smaller version of the same response.

A strong response is not yet a benefit. In the French EEG study above, an isochronic-style sound raised gamma power more than a gamma binaural beat over four minutes, but nobody tested whether listeners thought or remembered better. In the New York cycling study, a 40 Hz isochronic tone on a 440 Hz carrier, laid under the riders' own music, changed neither power output nor how energised they felt. The attention studies with 40 Hz sound that did find effects, at Leiden University, used binaural beats; they are described on the page “40 Hz binaural beats”.

The other reason people search for 40 Hz is Alzheimer's research. At the Massachusetts Institute of Technology, seven days of 40 Hz tones improved memory and reduced amyloid in mice bred to develop Alzheimer's-like changes, and sound combined with 40 Hz light cleared plaques more widely. Those tones were physically pulsed, the same principle as an isochronic tone, not binaural beats. But a team at New York University could not reproduce the effect of 40 Hz light in two mouse models, and in people a six-month trial of 76 patients found no difference from a sham device on its main measure. A trial of 670 patients had not published results as of 1 October 2026. A 40 Hz tone from a website is not a treatment for dementia.

If you want to try 40 Hz for focus, use a carrier of 300 to 400 Hz so the pulse keeps some pitch, keep the volume low, listen for a few minutes before a precise task and during its first block, and do not use it in the evening. Where gamma comes from, and why it is so hard to measure from the scalp, is explained on the page “Gamma waves”.

How to use the isochronic tone generator

The generator on this page opens in isochronic mode.

• Choose a preset or set the pulse rate with the slider.
• Set the carrier tone. A lower tone, 150 to 250 Hz, makes the pulse softer; a higher one makes it sharper.
• Start at a low volume. A pulsing sound seems louder than a steady one.
• Begin with 10 minutes. If the pulse feels comfortable, extend to 15 or 20.
• To compare with a binaural beat, put on headphones and switch the mode without stopping the sound.

If you want one steady tone without any pulse, for example to test a speaker or to hear a single pitch, use the “Tone generator” page.

Isochronic tones with music or nature sounds

A bare pulse can be tiring. Layering it under another sound softens it without removing the rhythm.

Play rain, a stream or quiet instrumental music from another device and keep the generator lower in volume than that sound. The pulse should be felt more than heard. Avoid music with a strong beat of its own: two rhythms compete.

Who should be careful with isochronic tones

Because the pulse is sharp, isochronic tones are more stimulating than binaural beats.

• Epilepsy. Rhythmic stimuli can trigger a seizure in some people with epilepsy. Talk to your doctor before listening.
• Headache and tinnitus. If the pulse brings on a headache or makes ringing in the ears worse, stop and try a binaural beat at a lower volume.
• Driving. Slow pulse rates make you sleepy. Do not listen while driving or operating machinery.
• Children. There is no research on isochronic tones in children; keep the volume low and the sessions short.
• Flashing lights. Some apps and headsets add a flicker to the pulse. Do not use flicker if you or a family member has epilepsy or has had a seizure.

Almost everything known about rhythm and seizures comes from light, not sound. A review for the Epilepsy Foundation of America found that about 0.3 to 3 % of people show an abnormal EEG response to flashing light, and that seizures triggered by light affect about 1 in 10,000 people, or 1 in 4,000 aged 5 to 24. Flash rates of 15 to 25 Hz are the most provocative, but anything from 1 to 65 Hz can do it. The same expert group's consensus treats flashing at 3 Hz or faster as a potential hazard when it is bright and fills a large part of the view, and doctors use flashing lights in the EEG laboratory precisely to test for this sensitivity.

These figures describe flicker. No comparable figures exist for pulsing sound, so they should not be read as the risk of an isochronic tone. They do apply in full to the light-and-sound devices sold for entrainment, such as the headset in the sleep study above. The generator on this page makes sound only.

Isochronic tones for ADHD

There are no controlled studies of isochronic tones in ADHD. The studies that exist used binaural beats, and their results were mixed: attention test scores did not change in children, while adults rated their studying as better.

A 2025 laboratory study then compared people with attention deficits and neurotypical people during a long attention task, under noise, a monaural beat and a binaural beat, while recording their EEG. Binaural beats brought no benefit, neither in behaviour nor in brain activity. All three studies are described on the page “Binaural beats”.

A lesson also comes from neurofeedback, where children learn to change their own brain waves. A 2016 meta-analysis of 13 trials with 520 children found improvements only in the least blinded ratings, made by people closest to the treatment; in probably blinded ratings and in trials with sham or active controls, the effect was not significant. In the largest double-blind trial, 142 children with ADHD improved a great deal, but those who trained on a fake signal improved just as much, and the two groups still did not differ after 13 and 25 months. When a rhythm-based method is tested carefully, expectation, attention and routine explain much of the benefit.

If a steady pulse helps you start a task, use it as you would use a metronome. It is an aid to getting started, not a treatment, and it does not replace medication, therapy or support at school or work. Test it honestly: study for a week with the pulse and a week with silence or plain noise, and compare how much you got done.