Carrier frequency · heard as pitch
220 Hz is an audible sound wave: air pressure completes 220 cycles per second and the ear perceives a pitch.
Consciousness Lab · EEG & neural signals
Same Hz. Different world.
No magic number here, just a careful look at rhythm, signal and experience.
Hear a gentle audible carrier whose level rises and falls at a selected rate, learn what EEG actually measures, and follow a neural message from dendrites to synapse, a clear connection between sound, science and personal experience.
Explanation and demonstrationPersonal experience for reflection
Before playing a sound
Three different phenomena share one unit
Hertz means cycles per second. To understand the number, ask what is repeating: a sound wave, a change in sound level, or a pattern in an EEG signal.
Modulation rate · how level pulses
10 Hz in this lab means the carrier level rises and falls ten times per second. We do not present 2, 6 or 10 Hz as standalone audible tones.
EEG rhythm · measured at the scalp
10 Hz in EEG is a recurring pattern in tiny voltage changes produced by coordinated cell populations, not a sound or a neuron's transmission speed.
Four listening lenses
Choose a rhythm. Hear a model. Notice what, if anything, you perceive.
Each eight-second sample uses the same 220 Hz carrier. Only the modulation rate changes, allowing comparison without music or video steering the experience.
Audible carrier 220HzAmplitude modulation8 seconds
Before pressing play, lower your device volume; actual loudness depends on the device, speakers or headphones.
8–13 Hz
Alpha
10 Hz · medium pulse
Personal association, not an outcome: alert calm, reduce external load and notice what remains clear and awake.
Posterior alpha activity is often seen during relaxed wakefulness and with eyes closed. It also changes with attention, expectation and sensory processing, so it is not a single signature of calm.
- Observation prompt
- Does the pulse feel smooth, clearly rhythmic, or almost like one continuous texture?
- Do not infer
- Playing 10 Hz does not automatically place the brain in an ‘alpha state.’
4–8 Hz
Theta
6 Hz · slow pulse
Personal association, not an outcome: imagery and inner journey, allow an image to arise and pass before interpreting it.
Theta appears in drowsiness and light sleep, while local theta patterns are also studied in memory, learning and cognitive control. Meaning depends on location, timing and task.
- Observation prompt
- Does the space between pulses leave more room for imagery, or pull attention outward?
- Do not infer
- ‘Inner journey’ is an experiential invitation, not theta's fixed biological meaning.
0.5–4 Hz
Delta
2 Hz · very slow pulse
Personal association, not an outcome: slowing and sleep, feel the long interval without trying to force sleep.
Delta activity is especially prominent in adult N3 deep sleep. It can appear in other contexts too, and interpretation depends on age, recording location and state.
- Observation prompt
- What stands out most: the carrier, the slow pulse, or the relative quiet between them?
- Do not infer
- A 2 Hz demonstration is not a sleep switch and cannot promise sleep onset or deep sleep.
30–80 Hz
Gamma
40 Hz · fast texture
Personal association, not an outcome: focus and cognitive arousal, notice whether the texture feels sharp, rough, activating or neutral.
40 Hz is used to study auditory steady-state responses, where parts of the auditory system follow the stimulus rhythm. Scalp gamma is also sensitive to muscle activity and technical artifacts.
- Observation prompt
- Can you still hear separate pulses, or have they merged into one rough timbre?
- Do not infer
- A 40 Hz auditory response does not prove improved focus, memory or disease treatment.
The visual wave is a calm illustration and does not move at the true rate, avoiding rapid flashing.
Choose one of four demonstrations. Audio starts only after a click.
Behind the sound
What does the system actually create?
The engine creates a 220 Hz sine wave and connects a slower oscillator that changes its level. The digital signal is attenuated, fades in and out, and closes automatically.
220 Hz carrier × amplitude envelope at 2 / 6 / 10 / 40 HzSpeakers or headphones
This is monaural amplitude modulation, so headphones are optional. Begin with low device volume.
This is not a binaural beat
With binaural beats, each ear receives a slightly different frequency and the difference is perceived as a beat. Here both sides receive the same modulated signal.
A demonstration, not a brain measurement
The system does not read EEG, know what your brain is doing, or attempt to prove that your brain has ‘moved to a frequency.’
From signal to synapse
How does information move from neuron to neuron?
No single wire carries a complete ‘thought.’ Each cell combines many messages, decides whether to fire, and shifts the probability that the next cell will act.
1 · Reception at dendrites
Receptors on dendrites and the cell body receive excitatory and inhibitory messages from potentially thousands of connections.
2 · Integration across time and space
Tiny voltage changes add and cancel. The location and timing of every input influence the result.
3 · Crossing threshold
When the axon initial segment crosses threshold, it produces a brief all-or-none action potential.
4 · Travel along the axon
Sequential sodium and potassium channel opening regenerates the impulse; with myelin, it advances between exposed nodes.
5 · Release at the synapse
Calcium enters the axon terminal, vesicles fuse with the membrane and neurotransmitters enter the synaptic cleft.
6 · The next cell changes
Transmitters bind receptors and alter voltage or signaling systems in the next cell, changing its likelihood of firing.
From millions of cells to one signal
What does EEG actually measure?
Scalp electrodes measure tiny voltage differences. The signal mainly reflects summed, coordinated postsynaptic activity in large populations of pyramidal cells, not a direct reading of a single action potential.
When a component repeats roughly ten times per second, it can be described as activity around 10 Hz. Yet several rhythms coexist at different locations and strengths; meaning comes from the full context.
EEG does not read thoughts. One band alone cannot establish emotion, level of consciousness, diagnosis or personality.A short dictionary
Four different meanings of frequency
| Term | What oscillates | Example |
|---|---|---|
| Carrier frequency | Air pressure | An audible 220 Hz tone |
| Amplitude modulation | The carrier's level | 220 Hz rising and falling ten times per second |
| Firing rate | A neuron's impulses over time | A rate changing with cell, stimulus and context |
| EEG rhythm | A pattern in the electrical signal of cell populations | Alpha activity around 8–13 Hz |
For anyone who wants to verify
Sources for verification and limits of evidence
Links open only if you choose them. Every essential explanation remains available on this page without leaving it.
The physiological basis of EEGAmerican Epilepsy Society / NCBI BookshelfThe action potentialStatPearls / NCBI BookshelfEncoding stimulus intensity in firing rateNeuroscience / NCBI BookshelfSystematic review of binaural beatsFourteen EEG studies with inconsistent results
Studies of rhythmic stimulation and binaural beats report mixed findings. A rhythm-following response during playback is not equivalent to treatment, cognitive improvement or a lasting effect.
Safe listening
Short demonstrations with an attenuated digital signal are for learning and observation, not medical treatment.
- Start with low device volume and stop immediately if you feel pain, dizziness, discomfort or ringing.
- Do not use a slowing demonstration while driving, operating equipment or in any situation requiring full alertness.
- This page is not a diagnostic tool or a substitute for medical advice, a hearing assessment or treatment.
The number is only the beginning.
With clear distinctions, curiosity and honesty can coexist, and a personal experience does not have to become a promise.
Continue to the Frequency Lab