4 Hz binaural beats benefits: what studies show

A 4 Hz binaural beat plays 108 Hz to one ear and 112 Hz to the other, and your hearing turns the difference into a slow pulse, four times a second: about the pace at which speech rises and falls. 4 Hz is where the brain's delta band ends and theta begins. No benefit is established; the few studies of beats near 4 Hz are small and disagree.

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Eleven long violet ribbons of light on a deep violet ground, rising in four gentle crests across the picture and never touching — Eleven ribbons in theta violet, drawn in code: one wave with four crests across the picture, one for each beat in a second of the 4 Hz recording.

What does 4 Hz mean?

4 Hz means four cycles a second, so one cycle lasts a quarter of a second, 250 milliseconds. The hertz only counts repeats. A sound wave, a flashing light, the rise and fall of a voice and an electrical rhythm in the brain can all run at 4 Hz, and each is a different thing.

In the brain's rhythms, 4 Hz sits exactly on a border. The clinical glossary of the International Federation of Clinical Neurophysiology puts delta below 4 Hz and theta from 4 to under 8 Hz, and gives a theta wave a length of 125 to 250 milliseconds (IFCN glossary). So a 4 Hz wave, 250 milliseconds long, is the slowest wave that still counts as theta. The same glossary lists bursts of 4 to 7 waves a second over the temples as a normal sign of drowsiness. The guide to theta waves follows the band from drowsiness to meditation, and the guide to 2 Hz covers the delta side of the line.

Most people who search for 4 Hz binaural beats want to know what they do. The honest short answer is that no benefit is established, and this guide shows why, study by study. It also shows something most guides leave out: you already hear 4 Hz every day.

Where do you already hear 4 Hz?

In speech. As someone talks, their voice gets louder and softer with each syllable, and that rise and fall has a pace. Across more than 25 hours of speech in nine languages, Ding and colleagues found the rise and fall of speech peaks broadly around 5 Hz, consistent from language to language, while Western music peaks around 2 Hz. A review by Giraud and Poeppel describes the same signature: the loudness of natural speech follows its syllables, and its modulation spectrum typically peaks between 4 and 7 Hz. They also describe how rhythms in the brain, theta among them, take part in following speech as it arrives.

We measured it ourselves, from open recordings. LibriSpeech is a free collection of English read aloud from audiobooks, recorded 16,000 times a second and shared under a Creative Commons licence. Its clean development set holds 2,703 recordings from 40 readers, 20 of them women, 5.4 hours in all. For every recording we traced how its loudness rose and fell, then measured how much of that movement happened at each pace from 0.5 to 32 Hz, in steps of a sixth of an octave. Each reader counts once, and the chart shows the middle value across readers.

How fast read English rises and falls, 0.5 to 32 Hz: the line climbs to a broad peak just under 4 Hz and falls away above 8 Hz — Read English rises and falls most at just under 4 Hz: the busiest band runs from 3.6 to 4.0 Hz, and 35 of the 40 readers peak between 2.5 and 5 Hz. Medians over the LibriSpeech readers, measured by Harmonance.

Share of the rise and fall in each band, per cent
Band centre	Median	Middle half
1.06 Hz	3.0	2.7 to 3.2
2.12 Hz	4.0	3.7 to 4.4
3.36 Hz	4.9	4.6 to 5.4
3.78 Hz (busiest)	5.1	4.6 to 5.5
4.24 Hz	4.7	4.3 to 5.2
5.99 Hz	3.7	3.1 to 4.2
8.48 Hz	2.3	2.0 to 2.8
16.95 Hz	0.7	0.6 to 0.9

The peak is broad, not a sharp line. Theta, 4 to under 8 Hz, holds 23 per cent of the rise and fall, and the slower range from 0.5 to 4 Hz holds 64 per cent, as medians across readers. Our peak sits a little below the 5 Hz Ding and colleagues found. The two need not match exactly: these are books read aloud, not conversation, and our method is simpler than theirs. Both agree on the main point. The slow pulse of a 4 Hz binaural beat runs at about the pace of the syllables you hear all day.

That is a fact about speech and hearing, not a promise about beats. A binaural beat carries no words, and no study has tested whether a 4 Hz beat does anything because speech moves at a similar pace.

How does a 4 Hz binaural beat work?

A 4 Hz binaural beat plays one steady tone in each ear, 4 Hz apart, and your hearing turns the difference into a beat. Harmonance's plays 108 Hz in the left ear and 112 Hz in the right. Neither ear hears a beat on its own; it forms only where the signals from the two ears meet, in the brainstem. Neurons of the superior olivary complex, which compare the timing of the two ears, fire at the rate of the difference, and Oster found the beats were heard only with tones below about 1,000 Hz (Chaieb and colleagues' review).

A quarter of a second of 108 Hz in the left ear and 112 Hz in the right, in step, opposite and in step again, then the brainstem, the sound and theta — In 250 milliseconds the left ear hears 27 waves of 108 Hz and the right ear 28 waves of 112 Hz, so the right gains one whole wave and the two fall in and out of step four times a second. The brainstem makes the beat from that difference; whether brain rhythms follow it is the open question.

The arithmetic is easy to check. 112 minus 108 is 4, so every quarter of a second the right ear's tone gains exactly one wave on the left's: crest meets crest at the start, crest meets trough at 125 milliseconds, and crest meets crest again at 250. Nine hours hold 129,600 beats.

How does it sound? A 2023 systematic review sums up the descriptions: up to 20 Hz a binaural beat is heard as a tone that rises and falls in loudness, and below 3 Hz as a tone that seems to rotate in the head from ear to ear. It adds that these limits are approximate and vary from person to person (Ingendoh and colleagues). So 4 Hz sits just above the rotating range: most people hear a low hum that swells and fades four times a second, and some may still hear a little movement. Played through a speaker, both tones reach both ears and mix in the air instead; the guide to binaural beats and isochronic tones explains the difference.

What is in Harmonance's 4 Hz recording?

Two pure tones, 108 Hz on the left and 112 Hz on the right, held for nine hours with nothing added. The 4 Hz low theta binaural beat plays it free, with no ads, and it is one of the pieces in the Binaural Beats collection.

The uploaded nine-hour master, measured
Moment	Left and right ear	Beat
First second	108.00 and 112.00 Hz	4.00 Hz
Halfway, 4 h 30 min	108.00 and 112.00 Hz	4.00 Hz
Last second	108.00 and 112.00 Hz	4.00 Hz

Read from the decoded audio of the uploaded master, 6,481 readings in all. The largest difference from the planned tones was 0.00053 Hz.

We checked the uploaded file itself, not only the recipe that made it. Its loudness reads -23 LUFS, and its peaks stay more than 21 dB below the loudest a recording can go. In each channel the other ear's tone sits at least 89 dB down, so the two tones never mix in the file: the beat forms only in your hearing. The steady rate is a listening choice. No study has played a 4 Hz beat for nine hours.

What are the benefits of 4 Hz binaural beats?

None is established. Websites credit 4 Hz with deep meditation, sleep, creativity, a release of brain chemicals and even extrasensory perception, usually because 4 Hz is a theta rate and theta appears in drowsy and meditative states. That reasoning assumes the brain falls into step with a beat, which is the very thing the studies below test. For the brain chemical and extrasensory claims, no study could be found at all.

The meditation claim has a famous counter-example. The best-known EEG study of long-term Tibetan Buddhist meditators found high-amplitude gamma activity, at 25 to 42 Hz, during their practice, not a slow theta rhythm (Lutz and colleagues).

Studies that played a beat at or near 4 Hz, oldest first
Study	What people heard	What was found
Lane and colleagues	29 people on a 30-minute watching task, beats at 1.5 and 4 Hz or at 16 and 24 Hz in pink noise	Fewer correct detections, more false alarms and a more negative mood with the slow beats
Le Scouarnec and colleagues	15 mildly anxious people at home for four weeks, music tapes with delta and theta beats, no comparison group	Daily diary ratings of feeling anxious fell; a standard questionnaire showed no significant change
Karino and colleagues	9 people, slow beats at 4.00 or 6.66 Hz, recorded as magnetic fields from the head	The cortex responded at the rate of the beat
López-Caballero and Escera	14 young adults, five beats for 3 minutes each, 4.53 Hz among them	No beat changed the EEG band that matched it
Ingendoh and colleagues	A review of 14 EEG studies at many rates, ten of them with theta beats	5 fitted entrainment, 8 did not, 1 was mixed

Five sources on slow beats. Most are small, the pilot with mildly anxious people had no comparison group, and none tests a 4 Hz beat on its own against a benefit people search for.

Read together, they point both ways. The one study with a measure of performance found slow beats at 1.5 and 4 Hz went with worse watchfulness and a lower mood than faster beats. The pilot with mildly anxious people reported calmer diaries, but with no comparison group, and the formal questionnaire did not move significantly. The widest pooled result, a 2019 meta-analysis of 22 studies, found a medium average effect across many beat rates and many kinds of task, and found that its direction and size depend on the rate, the listening time and when the listening happens. So it cannot say what a 4 Hz beat does on its own.

What a 4 Hz beat is, for certain, is a slow, steady sound with a pulse near the pace of speech, the same from the first minute to the last. Listen because you like how it sounds, and notice for yourself.

Does a 4 Hz beat change your brainwaves?

The brain does respond to it; whether its rhythms follow it is unsettled. In nine people, Karino and colleagues recorded the tiny magnetic fields of the cortex during slow beats of 4.00 and 6.66 Hz and found a response at the rate of the beat. That shows the hearing brain tracks the beat. It is a smaller claim than entrainment, the idea that the brain's own rhythms fall into step with it.

For entrainment, the evidence is mixed. López-Caballero and Escera played five beats for 3 minutes each, among them a 4.53 Hz theta beat on a 373 Hz tone, and saw no change in the EEG band matching any of them. The 2023 review found 14 EEG studies of binaural beats at many rates: five fitted entrainment, eight did not and one was mixed. Theta was the band tested most, in ten of the studies (Ingendoh and colleagues). The guide to theta waves sets out more of the theta studies, including three that point to a cost for memory.

Is it safe to listen to a 4 Hz binaural beat?

Two cautions come from the research. First, attention: in Lane and colleagues' study, people watching for targets made fewer correct detections and more false alarms with beats at 1.5 and 4 Hz than with faster beats, so never listen while driving or doing anything that needs your full attention. Second, volume: the World Health Organization's safe listening advice gives 80 dB as safe for up to 40 hours a week and suggests keeping a device below 60 per cent of its maximum. A nine-hour session every night for a week is 63 hours, so for long listening keep the level well below that.

How do you listen to a 4 Hz binaural beat?

Use headphones. The beat forms only when each ear gets its own tone. Turn off spatial audio or head tracking, and check that left and right are the right way round.
Keep it low. Set the volume just loud enough to hear the hum clearly, well inside the safe listening limits above.
Listen for the pulse. Start the 4 Hz beat, close your eyes and notice the hum swelling and fading. Then listen to someone talk, or read a page aloud, and notice the pace of the syllables beside it.
Keep a practice. In Studio you can set a timer and save the mixes you come back to.
Stop when you want to. Take the headphones off if anything feels uncomfortable.

If you prefer a beat that moves, the Falling Theta Session slows from 7 to 5 Hz over nine hours. Either side of 4 Hz, the 2 Hz delta beat sits in the delta band and the 6 Hz theta beat in the middle of theta. The guide to binaural beats covers what the reviews found across every rate, the guide to brainwave frequencies sets the bands side by side, and the guide to 10 Hz does for alpha what this guide does for 4 Hz.

Sources and limits

The chart measures 40 readers of English from audiobooks, one language read aloud, with a simple measure of loudness, so it shows the pace of read speech, not of every voice. It shows where 4 Hz sits in everyday hearing, not what any sound does to the brain. The studies of slow binaural beats are few and small, used different designs, rates and listening times, and none tested Harmonance's nine-hour recording.