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.

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.

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.

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.

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.

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.

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.

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.

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.

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.