If you’ve ever explored binaural beats for meditation, focus, or sleep, you may have come across terms like base frequency (also known as carrier frequency), offset frequency, and target frequency.
It sounds technical, but it's actually pretty easy. to understand. Moreover, understanding these three frequency concepts is key to knowing how binaural beats work, and how they can affect your brain.
This easy guide explains everything in simple, beginner-friendly language.
What Are Binaural Beats?
Here's a quick recap, in case you've forgotten or didn't know: A binaural beat occurs when you hear two slightly different sound frequencies, one in each ear.
Your brain doesn’t hear both tones separately, it perceives the mathematical difference between them as a rhythmic beat. This perceived rhythm is called the binaural beat.
Example:
- Left ear: 200 Hz
- Right ear: 205 Hz
- Brain perceives: 5 Hz
Result: Your brain follows along and is “entrained” to 5 Hz, which corresponds to a theta brainwave state (relaxation and meditation).
Simple, but effective.
Base Frequency vs. Offset Frequency vs. Target Frequency
Binaural beats are created using two related frequencies, and a third frequency is the desired outcome. Here's how it works:
1. Base Frequency (Carrier Frequency)
This is the steady, constant tone that plays in one ear (usually the left).
It forms the foundation of the sound.
Example: 200 Hz
The base frequency does not change, even if the track’s target frequency changes.
“Base frequency” means the same as “carrier frequency.”
2. Offset Frequency
This is the other tone played in the opposite ear.
It is slightly higher or lower than the base frequency.
Example: Base = 200 Hz, offset = 204 Hz
The difference between the base and offset is the target frequency. In this case, 4 Hz.
Dynamic Tracks
If the track changes frequency at some point, it is the offset frequency that changes while the base remains fixed. The change in frequency should happen gradually, to ensure a smooth progression of the binaural beat.
Example:
- Base: 200 Hz
- Offset starts at 208 Hz → Target frequency = 8 Hz
- Offset gradually decreases to 204 Hz → Target frequency change = 4 Hz
3. Target Frequency
This is the mathematical difference between the base and offset frequencies.
This is the binaural beat your brain actually perceives.
The target frequency determines the brainwave state:
Target Frequency Brainwave Effect:
- 0.5–4 Hz Delta Deep sleep, restoration
- 4–8 Hz Theta Meditation, calm, intuition
- 8–12 Hz Alpha Relaxation, creativity
- 12–30 Hz Beta Focus, concentration
- 30–100 Hz Gamma High-level cognition, 40 Hz gamma studies
Static vs. Dynamic Binaural Beats
Static:
This means that the target frequency remains constant. Both base and offset stay the same.
Example: Base 200 Hz, Offset 204 Hz → Target 4 Hz throughout.
Dynamic:
Target frequency changes gradually. Base stays fixed, offset changes.
Example:
Base 200 Hz, Offset 208 Hz → 204 Hz → 202 Hz, creating a beat that ramps down from 8 Hz → 4 Hz → 2 Hz.
This is useful for tracks that guide the brain through multiple states, e.g., starting relaxed and moving into deep meditation.
Why the Correct Base Frequency Matters
Even though the brain is focussed on binaural beat itself, the base frequency shapes the entire experience.
- Tone: Lower base frequencies are warmer and feel grounding; higher ones are higher pitched and feel more intense
- Ear fatigue: It is important producers choose a pleasant base frequency that harmonizes with the music to avoid listener fatigue.
Optimal Base Frequency Use
There is a table known as the Oster Curve, which loosely shows which base frequency is most effective for producing a perceptible/effective binaural beat at a given target frequency. In other words, it maps a suggested optimal base frequency to use depending on the brainwave frequency you want to achieve. It doesn't have to be followed exactly but it's a good guide.
The curve is the work of Dr. Gerald Oster, a biophysicist who published the landmark 1973 paper “Auditory Beats in the Brain” in Scientific American.
Oster didn’t create the curve as a “production guide” for music producers. His original purpose was scientific, not creative.
He wanted to understand:
- At which frequencies the brain can detect binaural beats most clearly
- How sensitivity changes depending on the base (carrier) frequency
- Whether certain frequency combinations make the binaural beat stronger or weaker
- The biological and neurological mechanisms behind auditory beat perception
At the time (early 1970s), very little was known about how the brain interprets two different tones presented separately to each ear. Oster’s work aimed to clarify this phenomenon.
From his research, he created a curve showing that: Lower target frequencies (like delta and theta) are perceived more strongly when paired with moderately low base frequencies. As the target frequency increases, the optimal base frequency also shifts.
You can see an example of the Oster Curve here.
I hope this information has helped you understand exactly how the frequency signals that create a binaural beat work, giving you a clearer sense of what’s happening while you listen.
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