639 Hz: the tone of connection and the heart chakra

What is 639 Hz

639 Hz is a tone that vibrates 639 times a second. In air its wave is 54 centimetres long.

You will not find it on a piano. The nearest key is D♯5, which sounds at 622.25 Hz, and 639 Hz lies 46 cents above it. A cent is a hundredth of a semitone, so 46 cents is almost halfway to the next key, E5. The tone falls into the gap between two keys.

In the set of nine solfeggio frequencies 639 Hz is the sixth from the bottom and the fourth of the six original tones. Its syllable is Fa. The number was put forward in the 1970s by Joseph Puleo and published in 1999 in the book he wrote with Leonard Horowitz.

Like all solfeggio numbers, 639 is tied to the others by arithmetic.

• The digits add up to 9: 6 + 3 + 9 = 18, and 1 + 8 = 9.
• It is made of the same digits as 396 and 963, in a different order.
• It stands 111 above 528 Hz and 102 below 741 Hz. The step to 741 is one of only two in the set that are not 111.

These patterns belong to the number. The ear hears a pitch, not a digit sum.

639 Hz meaning: what the tone is used for

In the tradition of sound therapy 639 Hz is the tone of connection. Practitioners use it for relationships, for reconciliation and for understanding between people.

In Russian-language sound therapy it has one more name: the frequency for attracting love. It is a name used by practitioners.

In practice people turn to the tone in these situations.

• Before a difficult conversation, to arrive calmer and more willing to listen.
• After a quarrel, as a few quiet minutes before you speak again.
• In a meditation on a person you want to make peace with.
• As a quiet background through a speaker when two people sit down to talk.

The tone does not do the talking for you. As the tradition sees it, it sets the mood in which talking becomes easier.

639 Hz and the heart chakra

Practitioners assign 639 Hz to the heart chakra, the centre in the middle of the chest that the tradition links with love and closeness to other people.

The tones are assigned to the chakras in order, from the bottom up.

Some schools assign the heart to 528 Hz, the tone called the love frequency. If you see both numbers under the name of the heart chakra, this is the reason: the schools differ.

A heart chakra session with 639 Hz is simple. Sit upright, put a hand on the middle of your chest, play the tone quietly and breathe slowly for 5 to 15 minutes.

639 Hz benefits: what research exists

No controlled studies in people have tested 639 Hz on its own. The benefits you read about, better relationships, reconciliation, more understanding, are what the tradition attributes to the tone.

That does not leave you with nothing. Three things are known about the neighbouring tone and about music.

• 528 Hz has been tested in people. In a Japanese study nine healthy adults listened for five minutes to soothing piano music tuned to 528 Hz. Cortisol, the stress hormone, fell, and oxytocin, the hormone linked with trust and closeness, rose. With the same kind of music tuned to 440 Hz neither change was significant. The study is small.
• In a trial in India 60 patients with stage 1 hypertension listened every day for a month to OM chanting composed at 528 Hz. Their pulse and blood pressure fell, their sleep improved and they felt less stress. The control group listened to nothing, so the study cannot separate the frequency from the chanting and from daily quiet listening.
• Music as such reduces stress. A review of 104 randomised trials with 9,617 participants found a medium effect on how people feel and a smaller one on the body, clearest in the heart rate.

None of these results belongs to 639 Hz. They show that quiet listening can calm the body. Whether 639 Hz adds something of its own has not been measured.

How to listen to 639 Hz

639 Hz is a bright tone in the upper half of the set. It is less sharp than 741, 852 and 963 Hz, and it still asks for a low volume.

• Turn the volume of your device down, choose 639 Hz in the generator and press Play.
• Raise the volume until the tone is barely audible. You should still hear your own breathing.
• Sit or lie down and close your eyes. Breathe in for a count of four and out for a count of six.
• Set the timer to 5 minutes for the first session. The sound fades out by itself.
• If the tone feels sharp, switch on the brown noise background.
• When 5 minutes feel comfortable, move to 15.

A speaker is enough for the pure tone. Headphones are needed only when you add a binaural beat.

639 Hz meditation for relationships

The main use of 639 Hz is a quiet session before or after contact with another person. This is a concrete setting for it.

For the first three minutes only breathe. Then bring to mind the person the session is about and stay with the picture without arguing with it. When your thoughts turn into a rehearsal of the quarrel, return to the sound.

For a slower, deeper meditation replace the alpha beat with the theta beat of 6 Hz. The page about binaural beats for meditation describes what the theta beat does.

639 Hz binaural beats

A binaural beat appears when each ear hears a slightly different tone. Both tones must be below 1000 Hz, so 639 Hz can serve as the carrier. In the generator the left ear hears 639 Hz and the right ear 639 Hz plus the beat.

The pitch you hear is the solfeggio tone; the slow pulse is the beat. The beat is the part with research behind it: a meta-analysis of 22 studies found a medium overall effect of binaural beats on memory, attention, anxiety and pain perception.

Headphones are required, because each ear must get its own tone.

639 Hz pure tone or 639 Hz music

A pure tone is one frequency and nothing else. It is exact and it is plain, and a plain sound tires the ear sooner than music. It suits short sessions and meditation on sound.

Music in 639 Hz is music tuned so that one of its notes falls on 639 Hz. Because 639 Hz lies between D♯5 and E5, an instrument in standard tuning cannot play such music; the piece has to be tuned away from the standard.

Music is easier to listen to for a long time, and the studies on stress used music and chanting, not a bare tone. For half an hour choose music, or the tone with the brown noise background. For five minutes of exact pitch choose the pure tone.

639 Hz tuning fork: how to use it

Solfeggio tuning forks are sold singly and in sets of nine. A 639 Hz fork gives the same tone as the generator, for 20 to 40 seconds after each strike.

• Strike the fork on a rubber activator or on the knee. Never strike it on a hard surface: metal on metal damages the fork and adds overtones.
• Hold an unweighted fork a few centimetres from the ear and listen until the sound fades.
• Place the stem of a weighted fork, the kind with discs on the prongs, on the breastbone in the middle of the chest. This is where the tradition places the heart chakra.
• Strike three to five times, with a few slow breaths between the strikes.

A fork is good for a short ritual. For a longer session, or for a beat and a background, use the generator.

639 Hz side effects: is it safe

No study has described a harm specific to a solfeggio frequency. Hearing is harmed by loudness and duration, not by a particular frequency. The World Health Organization considers sound of up to 80 dB safe for 40 hours a week.

What you can notice is a tired ear: a pure tone is more tiring than music at the same volume. The signs and what to do about them are these.

• Headache, irritation or ringing in the ears: lower the volume or stop.
• Tinnitus or sensitivity to sound: start with the low tones, 174 or 285 Hz, at a very low volume, and come to 639 Hz later.
• With a binaural beat: use headphones, do not listen while driving, and if you have epilepsy talk to your doctor first.

639 Hz compared with 528 Hz and 741 Hz

639 Hz stands between two better known neighbours. The table shows how the three differ.

Read from left to right, the tradition moves from harmony within yourself to connection with others and then to expression. If you are not sure where to start, start with 528 Hz: it is the lowest of the three and the one with studies in people. The page about 528 Hz has the details.