6 Hz Frequency: Theta Beat, Sound and Evidence

What is 6 Hz?

6 Hz is a rate: six cycles every second, so one cycle lasts a sixth of a second, 166.7 milliseconds. The number turns up in three places that are easy to mix up. In the brain, 6 Hz sits near the middle of theta, the band of electrical rhythms that the glossary of the International Federation of Clinical Neurophysiology (IFCN) sets at 4 to under 8 Hz, where a single wave lasts 125 to 250 milliseconds. In sound, 6 Hz is far below the lowest note you can hear. And in a binaural beat, 6 Hz is the difference between two tones you can hear perfectly well, one in each ear.

The ranges on the map

What	Range	Source
Theta band	4 to under 8 Hz	IFCN glossary
Infrasound	below 20 Hz	Møller and Pedersen
Binaural beats heard	about 1 to 30 Hz	Ingendoh, 2023
Tones that can make a beat	below about 1000 Hz	Ingendoh, 2023
Harmonance's 6 Hz beat	108 and 114 Hz	the 6 Hz page's recipe
The 6 Hz studies' tones	237 to 256 Hz	the studies below

Harmonance's 6 Hz theta binaural beat is the third kind. It plays 108 Hz in your left ear and 114 Hz in your right, free and with no account, and it is one of the steady beats in the Binaural Beats collection. The theta band itself, where its name comes from and what the brain is doing when theta grows, has its own guide: theta waves, meaning, meditation and evidence.

Can you hear a 6 Hz sound?

Not as a tone. Sound below 20 Hz is called infrasound, and Møller and Pedersen's review of hearing at low frequencies describes what happens as a tone gets lower: hearing becomes steadily less sensitive, "the tonal sensation ceases around 20 Hz, and below 10 Hz it is possible to perceive the single cycles of the sound". People can perceive infrasound only "if the level is sufficiently high", and at levels above that threshold they can feel vibration in the body as well.

So a loudspeaker playing a true 6 Hz wave at an everyday level gives you nothing to listen to. That is why a 6 Hz binaural beat is built the other way round: from two ordinary tones that your ears hear easily, whose difference is 6 Hz.

How does a 6 Hz binaural beat work?

Each ear hears its own steady tone, and your hearing compares them. Over one sixth of a second your left ear receives 18 waves of 108 Hz and your right ear 19 waves of 114 Hz, exactly one more. So the two tones start in step, drift until they are opposite, and come back into step: six times a second. You hear that drifting as a slow pulse or wobble, even though "no physical combination of the tones occurs outside the auditory system" (López-Caballero and Escera).

The two tones in one beat

Ear	Tone	Waves in one beat
Left	108 Hz	18
Right	114 Hz	19
Difference	6 Hz	1

The trick has limits. Binaural beats are heard from about 1 to 30 Hz, "a range that coincides with the main human EEG frequency bands", the two tones must be below about 1000 Hz, and the beats "seem to be best perceived" on tones of about 400 Hz, according to the 2023 systematic review by Ingendoh, Posny and Heine. Harmonance's tones, 108 and 114 Hz, are low and well inside that limit. Headphones matter: on speakers the two tones meet in the air before they reach you, and you hear an ordinary loudness beat instead. The guide to binaural beats and isochronic tones compares the two ways of making a pulse.

What is actually in the 6 Hz recording?

Two tones, and no 6 Hz at all. Harmonance measured the 6 Hz binaural master, the ten-minute recording of the recipe the page plays live and the nine-hour video was rendered from. Across the whole file the left channel reads 108.000 Hz and the right 114.000 Hz, each at -21.4 dB. At 6 Hz the left channel reads -210.7 dB and the right -189.6 dB: each at least 168 dB below its tone, under the smallest step a 24-bit file can store. Each ear's tone also sits 139.6 dB above any trace of the other ear's, so on headphones the two never meet before your ears.

What the master measures

Measured	Left ear	Right ear
Tone	108.000 Hz	114.000 Hz
Tone level	-21.4 dB	-21.4 dB
Level at 6 Hz	-210.7 dB	-189.6 dB
The other ear's tone	139.6 dB lower	139.6 dB lower

Download the measured spectrum (CSV)

Download one second of the mixed signal (CSV)

Mix the two channels, as a speaker does, and the picture changes in an instructive way. There is still no 6 Hz in the sound: the mixed signal reads -195.5 dB at 6 Hz. But its loudness now swells and fades 6.000 times a second, all the way to silence between swells, a modulation depth of 99.9999%. The 6 Hz is a pattern in time, not a sound of its own. The faint trace in the right channel at 6 Hz is the file's own rounding: at 48,000 samples a second, 114 Hz repeats exactly every sixth of a second, and so does the tiny error left by storing it in 24 bits.

The rest of the arithmetic is simple to redo. Nine hours is 32,400 seconds, so the nine-hour session holds 194,400 beats; in that time your right ear hears 3,693,600 waves and your left 3,499,200. The master is quiet by design: -23.0 LUFS integrated, its loudest moment 21.3 dB below the digital maximum, so your own volume control decides how loud it is.

What did studies of 6 Hz binaural beats find?

A handful of studies used exactly 6 Hz, or close to it. They agree that the brain registers the beat. They do not agree on much beyond that.

Studies of 6 Hz binaural beats

Study	What was played	What was found
Pratt and colleagues, 2009	3 and 6 Hz on 250 or 1000 Hz tones, two seconds each	brain responses that followed the beat, larger for 3 Hz and the lower tone
Karino and colleagues, 2006	4.00 and 6.66 Hz, nine people, magnetic recording	small responses at the beat rate
Jirakit­tayakorn and Wongsawat, 2017	6 Hz on 250 and 256 Hz, 30 minutes, 17 people, 11 in silence	theta up within 10 minutes and no higher after; mood scores mixed
Scala and colleagues, 2025	6 Hz on 237 and 243 Hz, 10 minutes, 20 people	6 Hz activity up at the back of the left side; the beat always came first
Amd, 2026	3, 6, 9 or 12 Hz on 250 Hz, five minutes, self-played, 101 people	only the 6 Hz group rated itself both calmer and more focused
Ingendoh and colleagues, 2023	a review of 14 EEG studies, every beat rate	5 for, 8 against, 1 mixed

The clearest evidence is that the beat can be recorded. Pratt and colleagues played 3 and 6 Hz beats on tones of 250 or 1000 Hz, each for two seconds, and recorded brain responses that followed the beat; they were larger for the slower beat and for the lower tone. Karino and colleagues picked up small magnetic responses at the beat rate in nine people listening to beats of 4.00 and 6.66 Hz.

Whether a 6 Hz beat raises theta across the brain is less certain. Jirakittayakorn and Wongsawat played 17 young adults a 6 Hz beat, 250 Hz in the left ear and 256 Hz in the right, for 30 minutes, while 11 others sat in silence. Theta power rose at nearly every scalp position within 10 minutes, and listening longer did not raise it further. Scala and colleagues gave 20 volunteers 10 minutes each of rest, a 6 Hz binaural beat on 237 and 243 Hz, a 6 Hz beat played to both ears and random noise; only the binaural beat raised 6 Hz activity, towards the back of the left side of the brain, and heart and breathing measures barely changed.

How people feel is the least settled of all. In two studies by Amd, students played the beats themselves for five minutes. Of four groups hearing 3, 6, 9 or 12 Hz, 101 people in all, only the 6 Hz group rated itself both calmer and more focused afterwards, and a second study of 118 found the same for 6 Hz with or without pink noise behind it. Across the field, the 2023 review counted 14 EEG studies of every beat rate: five supported the idea that the brain follows the beat, eight contradicted it and one was mixed.

What do the 6 Hz studies not show?

Quite a lot. Most are small, and each played the beat once, for between two seconds and 30 minutes. None used 108 Hz: their tones ran from 237 to 256 Hz, or higher, so no study has tested the beat this page plays. And each has a weakness its authors name.

• Scala's team note that the binaural beat always came first, so the change they saw "may have been due simply to the transition from silence to sound".
• Amd writes that the design lacked "control over potential expectancy effects", and that across all conditions of the second study 20 to 46% of written accounts described negative experiences.
• In Jirakittayakorn and Wongsawat's study, scores for anger, fatigue and confusion on a mood questionnaire were higher after the 30-minute session than before. The silent group also reported more anger and fatigue, after sitting still for 40 minutes, and the authors note that they tested a single session only.

So a 6 Hz beat is a sound with a measurable footprint in the brain, studied a little. It is not a proven way to bring on a state of mind. A 2019 meta-analysis of 22 studies put it in one line: "the direction and the magnitude of the effect depends upon the frequency used, time under exposure, and the moment in which the exposure takes place". Do binaural beats work? weighs that evidence across every band.

Where else does 6 Hz turn up in the brain?

In two patterns that brain specialists learn to recognise, both named for the number and both listed in the IFCN glossary as normal variants. The six hertz spike-and-slow-wave is a brief burst of complexes at 4 to 7 cycles a second, "but mostly at 6 c/s". The "fourteen and 6 Hz positive bursts" are seen "typically during drowsiness and light sleep, with incidence peaking in adolescence", and the glossary records that the pattern has been called "pseudo-epileptiform", meaning not associated with a liability to seizures. Neither has anything to do with a binaural beat: they are simply other places where six cycles a second shows up on a recording.

The better-known theta of drowsiness, problem solving and meditation is covered in the theta waves guide, and the guide to brainwave frequencies takes every band in turn.

How does 6 Hz compare with the other beats?

It is the steady middle of theta. The collection's other theta beats are the 4 Hz beat, at the edge of delta, and the 7.83 Hz Schumann resonance beat, near the top of the band; the Schumann resonance guide explains where that number comes from. The Falling Theta Session passes through 6 Hz on its way from 7 down to 5, and the 10 Hz beat sits one band up, in alpha. If you choose sound by mood rather than number, the reflective page of How do you feel? gathers tones people describe reaching for.

How should you listen to the 6 Hz beat?

Use headphones, so each ear hears only its own tone. Start with the volume low, lower than you think, and stop if anything feels uncomfortable. Keep it quiet for long sessions: sounds at or below 70 A-weighted decibels, "even after long exposure, are unlikely to cause hearing loss", while long or repeated exposure at 85 or more can cause it (NIDCD). Do not listen while driving or doing anything that needs your full attention. Then press play on the 6 Hz page and notice what you notice.

Sources and limits

Every outside source was opened and its words checked on the day this guide was written. Each one is linked where it is used above.

• Bands, waves and the two 6 Hz patterns: the IFCN glossary of EEG terms (Kane and colleagues, 2017).
• Hearing below 20 Hz: Møller and Pedersen (2004), a review.
• How binaural beats form and where they are heard: López-Caballero and Escera (2017) and the 2023 systematic review by Ingendoh, Posny and Heine, which reports the 1000 Hz limit and the 400 Hz best tone from earlier studies. The frequency map's range of hearing, about 20 to 20,000 Hz, is as Amd (2026) gives it.
• Studies of 6 Hz beats: Pratt and colleagues (2009), Karino and colleagues (2006), Jirakittayakorn and Wongsawat (2017), Scala and colleagues (2025), Amd (2026) and the 2019 meta-analysis. Most are small; their tones were 237 Hz or higher, never 108 Hz; none played a beat for longer than 30 minutes.
• Listening levels: NIDCD on noise-induced hearing loss.
• The recording's numbers: Harmonance's own measurement of the 6 Hz binaural master (119 spectra of 10 seconds averaged, levels relative to a full-scale sine wave), and arithmetic from its two tones. The measured spectrum and the mixed signal are downloadable beside the chart.